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	<updated>2026-05-06T08:43:15Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=242&amp;oldid=prev</id>
		<title>Rational Point: good and bad reduction: needs another article</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=242&amp;oldid=prev"/>
		<updated>2025-01-08T07:44:37Z</updated>

		<summary type="html">&lt;p&gt;good and bad reduction: needs another article&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 07:44, 8 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l9&quot;&gt;Line 9:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 9:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;with the &amp;#039;&amp;#039;&amp;#039;exponent&amp;#039;&amp;#039;&amp;#039; &amp;#039;&amp;#039;f&amp;#039;&amp;#039;&amp;lt;sub&amp;gt;&amp;#039;&amp;#039;p&amp;#039;&amp;#039;&amp;lt;/sub&amp;gt; of each prime &amp;#039;&amp;#039;p&amp;#039;&amp;#039; given by&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;with the &amp;#039;&amp;#039;&amp;#039;exponent&amp;#039;&amp;#039;&amp;#039; &amp;#039;&amp;#039;f&amp;#039;&amp;#039;&amp;lt;sub&amp;gt;&amp;#039;&amp;#039;p&amp;#039;&amp;#039;&amp;lt;/sub&amp;gt; of each prime &amp;#039;&amp;#039;p&amp;#039;&amp;#039; given by&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[good reduction]]” &lt;/del&gt;at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[multiplicative reduction]]” &lt;/del&gt;at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[additive reduction]]” &lt;/del&gt;at &#039;&#039;p&#039;&#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “additive reduction” at &#039;&#039;p&#039;&#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“good reduction” &lt;/ins&gt;at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“multiplicative reduction” &lt;/ins&gt;at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“additive reduction” &lt;/ins&gt;at &#039;&#039;p&#039;&#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “additive reduction” at &#039;&#039;p&#039;&#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &amp;#039;&amp;#039;The Arithmetic of Elliptic Curves.&amp;#039;&amp;#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &amp;#039;&amp;#039;The Annals of Mathematics,&amp;#039;&amp;#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &amp;#039;&amp;#039;American Journal of Mathematics,&amp;#039;&amp;#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles &amp;#039;&amp;#039;p&amp;#039;&amp;#039;-minimaux des variétés abéliennes.» &amp;#039;&amp;#039;Séminaire Bourbaki,&amp;#039;&amp;#039;  vol. 7, no. 227, 1962, 16 pp. http://www.numdam.org/item/?id=SB_1961-1962__7__65_0&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &amp;#039;&amp;#039;Publications Mathématiques de l&amp;#039;IHÉS&amp;#039;&amp;#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; among other “monstrous moonshine” literature of the period for a “precise” definition.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &amp;#039;&amp;#039;The Arithmetic of Elliptic Curves.&amp;#039;&amp;#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &amp;#039;&amp;#039;The Annals of Mathematics,&amp;#039;&amp;#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &amp;#039;&amp;#039;American Journal of Mathematics,&amp;#039;&amp;#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles &amp;#039;&amp;#039;p&amp;#039;&amp;#039;-minimaux des variétés abéliennes.» &amp;#039;&amp;#039;Séminaire Bourbaki,&amp;#039;&amp;#039;  vol. 7, no. 227, 1962, 16 pp. http://www.numdam.org/item/?id=SB_1961-1962__7__65_0&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &amp;#039;&amp;#039;Publications Mathématiques de l&amp;#039;IHÉS&amp;#039;&amp;#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; among other “monstrous moonshine” literature of the period for a “precise” definition.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l15&quot;&gt;Line 15:&lt;/td&gt;
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&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[bad reduction]]s” &lt;/del&gt;are possible on any one elliptic curve &#039;&#039;E&#039;&#039;.  A particular algorithm of Tate &amp;lt;ref&amp;gt;J. Tate, Bryan J. Birch and Willem Kuyk. “Algorithm for determining the type of a singular fiber in an elliptic pencil.” &#039;&#039;Modular Functions of One Variable IV&#039;&#039;, Springer, 1975. pp. 33-52.&amp;lt;/ref&amp;gt; is supposed to find the minimal [[Weierstraß normal form|Weierstraß form]] of the elliptic curve and calculate &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; for the last few special cases of bad reduction with wild ramification, in order to fully complete the definition of the &#039;&#039;&#039;conductor&#039;&#039;&#039;, assuming an impartial outsider can ascertain exactly what is meant by vague terms such as &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“good” or “bad &lt;/del&gt;reduction.“&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“bad reductions” &lt;/ins&gt;are possible on any one elliptic curve &#039;&#039;E&#039;&#039;.  A particular algorithm of Tate &amp;lt;ref&amp;gt;J. Tate, Bryan J. Birch and Willem Kuyk. “Algorithm for determining the type of a singular fiber in an elliptic pencil.” &#039;&#039;Modular Functions of One Variable IV&#039;&#039;, Springer, 1975. pp. 33-52.&amp;lt;/ref&amp;gt; is supposed to find the minimal [[Weierstraß normal form|Weierstraß form]] of the elliptic curve and calculate &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; for the last few special cases of bad reduction with wild ramification, in order to fully complete the definition of the &#039;&#039;&#039;conductor&#039;&#039;&#039;, assuming an impartial outsider can ascertain exactly what is meant by vague terms such as &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[good and bad &lt;/ins&gt;reduction&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;]]&lt;/ins&gt;.“&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=232&amp;oldid=prev</id>
		<title>Rational Point: Tate&#039;s algorithm</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=232&amp;oldid=prev"/>
		<updated>2025-01-07T11:56:14Z</updated>

		<summary type="html">&lt;p&gt;Tate&amp;#039;s algorithm&lt;/p&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 11:56, 7 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l15&quot;&gt;Line 15:&lt;/td&gt;
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&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of “[[bad reduction]]s” are possible on any one elliptic curve &#039;&#039;E&#039;&#039;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of “[[bad reduction]]s” are possible on any one elliptic curve &#039;&#039;E&#039;&#039;. &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt; A particular algorithm of Tate &amp;lt;ref&amp;gt;J. Tate, Bryan J. Birch and Willem Kuyk. “Algorithm for determining the type of a singular fiber in an elliptic pencil.” &#039;&#039;Modular Functions of One Variable IV&#039;&#039;, Springer, 1975. pp. 33-52.&amp;lt;/ref&amp;gt; is supposed to find the minimal [[Weierstraß normal form|Weierstraß form]] of the elliptic curve and calculate &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; and &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;3&amp;lt;/sub&amp;gt; for the last few special cases of bad reduction with wild ramification, in order to fully complete the definition of the &#039;&#039;&#039;conductor&#039;&#039;&#039;, assuming an impartial outsider can ascertain exactly what is meant by vague terms such as “good” or “bad reduction.“&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=206&amp;oldid=prev</id>
		<title>Rational Point: more minimal models</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=206&amp;oldid=prev"/>
		<updated>2025-01-05T16:55:25Z</updated>

		<summary type="html">&lt;p&gt;more minimal models&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 16:55, 5 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l11&quot;&gt;Line 11:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 11:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “[[good reduction]]” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “[[multiplicative reduction]]” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “[[additive reduction]]” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive reduction” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “[[good reduction]]” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “[[multiplicative reduction]]” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “[[additive reduction]]” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive reduction” at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &#039;&#039;Publications Mathématiques de l&#039;IHÉS&#039;&#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; among other “monstrous moonshine” literature of the period for a “precise” definition.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;lt;ref&amp;gt;André Néron. «Modèles &#039;&#039;p&#039;&#039;-minimaux des variétés abéliennes.» &#039;&#039;Séminaire Bourbaki,&#039;&#039;  vol. 7, no. 227, 1962, 16 pp. http://www.numdam.org/item/?id=SB_1961-1962__7__65_0&amp;lt;/ref&amp;gt;&lt;/ins&gt;&amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &#039;&#039;Publications Mathématiques de l&#039;IHÉS&#039;&#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; among other “monstrous moonshine” literature of the period for a “precise” definition.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=202&amp;oldid=prev</id>
		<title>Rational Point: soft math</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=202&amp;oldid=prev"/>
		<updated>2025-01-05T09:05:38Z</updated>

		<summary type="html">&lt;p&gt;soft math&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 09:05, 5 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Category:Properties]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Category:Properties]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;:&#039;&#039; &#039;&#039;&#039;Caveat emptor: &#039;&#039;&#039; This is an incomplete definition which has never been fully elicited or nailed down outside of a certain highly insular “[[monstrous moonshine]] groupie” community of “[[soft math]]” researchers. The working goal here would be to develop a simple, self-contained and rigorous definition suitable for outside work. &#039;&#039;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The &amp;#039;&amp;#039;&amp;#039;conductor&amp;#039;&amp;#039;&amp;#039; &amp;lt;ref&amp;gt;PlanetMath: conductor of an elliptic curve. https://planetmath.org/conductorofanellipticcurve&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Wikipedia: Conductor of an elliptic curve. https://en.wikipedia.org/wiki/Conductor_of_an_elliptic_curve&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The &amp;#039;&amp;#039;&amp;#039;conductor&amp;#039;&amp;#039;&amp;#039; &amp;lt;ref&amp;gt;PlanetMath: conductor of an elliptic curve. https://planetmath.org/conductorofanellipticcurve&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Wikipedia: Conductor of an elliptic curve. https://en.wikipedia.org/wiki/Conductor_of_an_elliptic_curve&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;LMFDB: Knowledge → ec → Conductor of an elliptic curve (reviewed). https://www.lmfdb.org/knowledge/show/ec.conductor&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Silverman, Joseph H., and Brumer, Armand. &quot;The number of elliptic curves over Q with conductor N..&quot; Manuscripta mathematica 91.1 (1996): 95-102. http://eudml.org/doc/156217.&amp;lt;/ref&amp;gt; of an elliptic curve &#039;&#039;E&#039;&#039; over a field &#039;&#039;K&#039;&#039; is an integer, (or an &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“ideal” &lt;/del&gt;of the ring of integers in any algebraic field,) defined by its prime factorization:&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;LMFDB: Knowledge → ec → Conductor of an elliptic curve (reviewed). https://www.lmfdb.org/knowledge/show/ec.conductor&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Silverman, Joseph H., and Brumer, Armand. &quot;The number of elliptic curves over Q with conductor N..&quot; Manuscripta mathematica 91.1 (1996): 95-102. http://eudml.org/doc/156217.&amp;lt;/ref&amp;gt; of an elliptic curve &#039;&#039;E&#039;&#039; over a field &#039;&#039;K&#039;&#039; is an integer, (or an &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[ideal]]” &lt;/ins&gt;of the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[&lt;/ins&gt;ring of integers&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;]] &lt;/ins&gt;in any algebraic field,) defined by its prime factorization:&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;N=\prod_{\mathrm{all\;primes\;} p}p^{f_p}&amp;lt;/math&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;N=\prod_{\mathrm{all\;primes\;} p}p^{f_p}&amp;lt;/math&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;where &lt;/del&gt;the &#039;&#039;&#039;exponent&#039;&#039;&#039; &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;&#039;&#039;p&#039;&#039;&amp;lt;/sub&amp;gt; of each prime &#039;&#039;p&#039;&#039; &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;is &lt;/del&gt;given by&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;with &lt;/ins&gt;the &#039;&#039;&#039;exponent&#039;&#039;&#039; &#039;&#039;f&#039;&#039;&amp;lt;sub&amp;gt;&#039;&#039;p&#039;&#039;&amp;lt;/sub&amp;gt; of each prime &#039;&#039;p&#039;&#039; given by&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“good” &lt;/del&gt;reduction at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“multiplicative” &lt;/del&gt;reduction at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“additive” &lt;/del&gt;reduction at &#039;&#039;p&#039;&#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“additive” reduction &lt;/del&gt;at &#039;&#039;p&#039;&#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[good &lt;/ins&gt;reduction&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;]]” &lt;/ins&gt;at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[multiplicative &lt;/ins&gt;reduction&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;]]” &lt;/ins&gt;at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[additive &lt;/ins&gt;reduction&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;]]” &lt;/ins&gt;at &#039;&#039;p&#039;&#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“additive reduction” &lt;/ins&gt;at &#039;&#039;p&#039;&#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &amp;#039;&amp;#039;The Arithmetic of Elliptic Curves.&amp;#039;&amp;#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &amp;#039;&amp;#039;The Annals of Mathematics,&amp;#039;&amp;#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &amp;#039;&amp;#039;American Journal of Mathematics,&amp;#039;&amp;#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &amp;#039;&amp;#039;Publications Mathématiques de l&amp;#039;IHÉS&amp;#039;&amp;#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; among other “monstrous moonshine” literature of the period for a “precise” definition.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &amp;#039;&amp;#039;The Arithmetic of Elliptic Curves.&amp;#039;&amp;#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &amp;#039;&amp;#039;The Annals of Mathematics,&amp;#039;&amp;#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &amp;#039;&amp;#039;American Journal of Mathematics,&amp;#039;&amp;#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &amp;#039;&amp;#039;Publications Mathématiques de l&amp;#039;IHÉS&amp;#039;&amp;#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; among other “monstrous moonshine” literature of the period for a “precise” definition.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l13&quot;&gt;Line 13:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 15:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“bad” reductions &lt;/del&gt;are possible on &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;an &lt;/del&gt;elliptic curve &#039;&#039;E&#039;&#039;.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“[[bad reduction]]s” &lt;/ins&gt;are possible on &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;any one &lt;/ins&gt;elliptic curve &#039;&#039;E&#039;&#039;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=200&amp;oldid=prev</id>
		<title>Rational Point: monstrous moonshine</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=200&amp;oldid=prev"/>
		<updated>2025-01-05T04:21:51Z</updated>

		<summary type="html">&lt;p&gt;monstrous moonshine&lt;/p&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 04:21, 5 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l9&quot;&gt;Line 9:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 9:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &#039;&#039;Publications Mathématiques de l&#039;IHÉS&#039;&#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; for a &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;precise &lt;/del&gt;definition.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; who in turn rely on the minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &#039;&#039;Publications Mathématiques de l&#039;IHÉS&#039;&#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;among other “monstrous moonshine” literature of the period &lt;/ins&gt;for a &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;“precise” &lt;/ins&gt;definition.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=199&amp;oldid=prev</id>
		<title>Rational Point: another primary reference</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=199&amp;oldid=prev"/>
		<updated>2025-01-05T04:09:30Z</updated>

		<summary type="html">&lt;p&gt;another primary reference&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr class=&quot;diff-title&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 04:09, 5 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l9&quot;&gt;Line 9:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 9:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+\delta_p&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; on the precise definition.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;who in turn rely &lt;/ins&gt;on the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;minimal models of Néron &amp;lt;ref&amp;gt;André Néron. «Modèles minimaux des variétés abéliennes sur les corps locaux et globaux.» &#039;&#039;Publications Mathématiques de l&#039;IHÉS&#039;&#039;, vol. 21 (1964), pp. 5-128. http://www.numdam.org/item/PMIHES_1964__21__5_0/ &amp;lt;/ref&amp;gt; for a &lt;/ins&gt;precise definition.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.png]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=197&amp;oldid=prev</id>
		<title>Rational Point: fix graphic</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=197&amp;oldid=prev"/>
		<updated>2025-01-04T23:46:33Z</updated>

		<summary type="html">&lt;p&gt;fix graphic&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr class=&quot;diff-title&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 23:46, 4 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l11&quot;&gt;Line 11:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 11:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &amp;#039;&amp;#039;The Arithmetic of Elliptic Curves.&amp;#039;&amp;#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &amp;#039;&amp;#039;The Annals of Mathematics,&amp;#039;&amp;#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &amp;#039;&amp;#039;American Journal of Mathematics,&amp;#039;&amp;#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; on the precise definition.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &amp;#039;&amp;#039;The Arithmetic of Elliptic Curves.&amp;#039;&amp;#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &amp;#039;&amp;#039;The Annals of Mathematics,&amp;#039;&amp;#039; 2nd series, vol. 88, no. 3, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &amp;#039;&amp;#039;American Journal of Mathematics,&amp;#039;&amp;#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; on the precise definition.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;svg&lt;/del&gt;]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;png&lt;/ins&gt;]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of “bad” reductions are possible.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Only a finite number of “bad” reductions are possible &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;on an elliptic curve &#039;&#039;E&#039;&#039;&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=194&amp;oldid=prev</id>
		<title>Rational Point: authoritative references</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=194&amp;oldid=prev"/>
		<updated>2025-01-04T23:36:27Z</updated>

		<summary type="html">&lt;p&gt;authoritative references&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 23:36, 4 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l7&quot;&gt;Line 7:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 7:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where the &amp;#039;&amp;#039;&amp;#039;exponent&amp;#039;&amp;#039;&amp;#039; &amp;#039;&amp;#039;f&amp;#039;&amp;#039;&amp;lt;sub&amp;gt;&amp;#039;&amp;#039;p&amp;#039;&amp;#039;&amp;lt;/sub&amp;gt; of each prime &amp;#039;&amp;#039;p&amp;#039;&amp;#039; is given by&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;where the &amp;#039;&amp;#039;&amp;#039;exponent&amp;#039;&amp;#039;&amp;#039; &amp;#039;&amp;#039;f&amp;#039;&amp;#039;&amp;lt;sub&amp;gt;&amp;#039;&amp;#039;p&amp;#039;&amp;#039;&amp;lt;/sub&amp;gt; of each prime &amp;#039;&amp;#039;p&amp;#039;&amp;#039; is given by&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “good” reduction at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “multiplicative” reduction at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;+??&lt;/del&gt;&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “additive” reduction at &#039;&#039;p&#039;&#039; &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;= 2 or &lt;/del&gt;3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;???&lt;/del&gt;&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “additive” reduction at &#039;&#039;p&#039;&#039; &lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;amp;gt&lt;/del&gt;; 3&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;;&lt;/del&gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “good” reduction at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “multiplicative” reduction at &#039;&#039;p&#039;&#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “additive” reduction at &#039;&#039;p&#039;&#039; &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&amp;amp;gt; &lt;/ins&gt;3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;\delta_p&lt;/ins&gt;&amp;lt;/math&amp;gt; if &#039;&#039;E&#039;&#039; has “additive” reduction at &#039;&#039;p&#039;&#039; &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;= 2 or 3&lt;/ins&gt;;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;where &amp;lt;math&amp;gt;\delta_p&amp;lt;/math&amp;gt; is some &amp;lt;u&amp;gt;measure of “wild ramification” in the action of the inertia group&amp;lt;/u&amp;gt;  on &amp;lt;math&amp;gt;T_\ell(E)&amp;lt;/math&amp;gt; for which Silverman &amp;lt;ref&amp;gt;Joseph H. Silverman. &#039;&#039;The Arithmetic of Elliptic Curves.&#039;&#039; Springer-Verlag, New York, 1986, corrected 2nd printing, p. 361.&amp;lt;/ref&amp;gt; refers to Serre and Tate &amp;lt;ref&amp;gt;Jean-Pierre Serre and John Tate. “Good reduction of Abelian varieties.” &#039;&#039;The Annals of Mathematics,&#039;&#039; 2nd series, vol. 88, no. &lt;/ins&gt;3&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;, Nov 1968, pp. 492-517.&amp;lt;/ref&amp;gt; and Ogg &amp;lt;ref&amp;gt;A. P. Ogg. “Elliptic curves and wild ramification.” &#039;&#039;American Journal of Mathematics,&#039;&#039; vol. 89, no. 1, Jan 1967, pp. 1-21.&amp;lt;/ref&amp;gt; on the precise definition.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.svg]]&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;[[Image:Conductor.svg]]&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;del style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&#039;&#039;&#039; &#039;&#039;N.B.&#039;&#039;:&#039;&#039;&#039; The definition here is incomplete and more authoritative references on the advanced abstract algebra should be consulted. All types of reduction at each prime &#039;&#039;p&#039;&#039; that are not “good” are said to be “bad,” and there are several special cases; only &lt;/del&gt;a finite number of “bad” reductions are possible.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;Only &lt;/ins&gt;a finite number of “bad” reductions are possible.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=193&amp;oldid=prev</id>
		<title>Rational Point: delineation graph</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=193&amp;oldid=prev"/>
		<updated>2025-01-04T22:10:45Z</updated>

		<summary type="html">&lt;p&gt;delineation graph&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 22:10, 4 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l8&quot;&gt;Line 8:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 8:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+??&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+???&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+??&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+???&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[Image:Conductor.svg]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&amp;#039;&amp;#039;&amp;#039; &amp;#039;&amp;#039;N.B.&amp;#039;&amp;#039;:&amp;#039;&amp;#039;&amp;#039; The definition here is incomplete and more authoritative references on the advanced abstract algebra should be consulted. All types of reduction at each prime &amp;#039;&amp;#039;p&amp;#039;&amp;#039; that are not “good” are said to be “bad,” and there are several special cases; only a finite number of “bad” reductions are possible.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&amp;#039;&amp;#039;&amp;#039; &amp;#039;&amp;#039;N.B.&amp;#039;&amp;#039;:&amp;#039;&amp;#039;&amp;#039; The definition here is incomplete and more authoritative references on the advanced abstract algebra should be consulted. All types of reduction at each prime &amp;#039;&amp;#039;p&amp;#039;&amp;#039; that are not “good” are said to be “bad,” and there are several special cases; only a finite number of “bad” reductions are possible.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
	<entry>
		<id>https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=189&amp;oldid=prev</id>
		<title>Rational Point: fw</title>
		<link rel="alternate" type="text/html" href="https://www.ellipticcurve.info/index.php?title=Conductor&amp;diff=189&amp;oldid=prev"/>
		<updated>2025-01-04T14:12:23Z</updated>

		<summary type="html">&lt;p&gt;fw&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
				&lt;tr class=&quot;diff-title&quot; lang=&quot;en&quot;&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 14:12, 4 January 2025&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l1&quot;&gt;Line 1:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 1:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[Category:Properties]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The &amp;#039;&amp;#039;&amp;#039;conductor&amp;#039;&amp;#039;&amp;#039; &amp;lt;ref&amp;gt;PlanetMath: conductor of an elliptic curve. https://planetmath.org/conductorofanellipticcurve&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Wikipedia: Conductor of an elliptic curve. https://en.wikipedia.org/wiki/Conductor_of_an_elliptic_curve&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The &amp;#039;&amp;#039;&amp;#039;conductor&amp;#039;&amp;#039;&amp;#039; &amp;lt;ref&amp;gt;PlanetMath: conductor of an elliptic curve. https://planetmath.org/conductorofanellipticcurve&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Wikipedia: Conductor of an elliptic curve. https://en.wikipedia.org/wiki/Conductor_of_an_elliptic_curve&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;LMFDB: Knowledge → ec → Conductor of an elliptic curve (reviewed). https://www.lmfdb.org/knowledge/show/ec.conductor&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Silverman, Joseph H., and Brumer, Armand. &amp;quot;The number of elliptic curves over Q with conductor N..&amp;quot; Manuscripta mathematica 91.1 (1996): 95-102. http://eudml.org/doc/156217.&amp;lt;/ref&amp;gt; of an elliptic curve &amp;#039;&amp;#039;E&amp;#039;&amp;#039; over a field &amp;#039;&amp;#039;K&amp;#039;&amp;#039; is an integer, (or an “ideal” of the ring of integers in any algebraic field,) defined by its prime factorization:&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;LMFDB: Knowledge → ec → Conductor of an elliptic curve (reviewed). https://www.lmfdb.org/knowledge/show/ec.conductor&amp;lt;/ref&amp;gt;&amp;lt;ref&amp;gt;Silverman, Joseph H., and Brumer, Armand. &amp;quot;The number of elliptic curves over Q with conductor N..&amp;quot; Manuscripta mathematica 91.1 (1996): 95-102. http://eudml.org/doc/156217.&amp;lt;/ref&amp;gt; of an elliptic curve &amp;#039;&amp;#039;E&amp;#039;&amp;#039; over a field &amp;#039;&amp;#039;K&amp;#039;&amp;#039; is an integer, (or an “ideal” of the ring of integers in any algebraic field,) defined by its prime factorization:&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l8&quot;&gt;Line 8:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 9:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+??&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+???&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;:&amp;lt;math&amp;gt;f_p=0&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “good” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=1&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “multiplicative” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039;;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+??&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; = 2 or 3;&amp;lt;br&amp;gt;&amp;lt;math&amp;gt;f_p=2+???&amp;lt;/math&amp;gt; if &amp;#039;&amp;#039;E&amp;#039;&amp;#039; has “additive” reduction at &amp;#039;&amp;#039;p&amp;#039;&amp;#039; &amp;amp;gt; 3;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;−&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #ffe49c; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&#039;&#039;&#039; &#039;&#039;N.B.&#039;&#039;:&#039;&#039;&#039; The definition here is incomplete and more authoritative references on the abstract algebra should be consulted. All types of reduction at each prime &#039;&#039;p&#039;&#039; that are not “good” are said to be “bad,” and there are several special cases; only a finite number of “bad” reductions are possible.&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&#039;&#039;&#039; &#039;&#039;N.B.&#039;&#039;:&#039;&#039;&#039; The definition here is incomplete and more authoritative references on the &lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;advanced &lt;/ins&gt;abstract algebra should be consulted. All types of reduction at each prime &#039;&#039;p&#039;&#039; that are not “good” are said to be “bad,” and there are several special cases; only a finite number of “bad” reductions are possible&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;.&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt; &lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;This all needs to be simplified and brought down from any excessive abstraction. Cryptography is a martial art. References are inconsistent, disinformation exists, and it is unwise to accept mathematical results on face value which one does not prove oneself, or work through and satisfy oneself with the proofs. If anything is too difficult, another tack needs to be taken, a plan of attack from a different position.  It is that strange feeling of invading a foreign library and opening up books one is not really welcome to&lt;/ins&gt;.&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Rational Point</name></author>
	</entry>
</feed>