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<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Primitive permutation group</span></span>
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<p>In <a href="Mathematics" title="Mathematics">mathematics</a>, a <a href="Permutation_group" title="Permutation group">permutation group</a> <i>G</i> <a href="Group_action" title="Group action">acting</a> on a non-empty finite set <i>X</i> is called <b>primitive</b> if <i>G</i> acts <a href="Transitive_action" class="mw-redirect" title="Transitive action">transitively</a> on <i>X</i> and the only <a href="Partition_of_a_set" title="Partition of a set">partitions</a> the <i>G</i>-action preserves are the trivial partitions into either a single set or into |<i>X</i>| singleton sets. Otherwise, if <i>G</i> is transitive and <i>G</i> does preserve a nontrivial partition, <i>G</i> is called <b>imprimitive</b>.
</p><p>While primitive permutation groups are transitive, not all transitive permutation groups are primitive. The simplest example is the <a href="Klein_four-group" title="Klein four-group">Klein four-group</a> acting on the vertices of a square, which preserves the partition into diagonals. On the other hand, if a permutation group preserves only trivial partitions, it is transitive, except in the case of the <a href="Trivial_group" title="Trivial group">trivial group</a> acting on a 2-element set. This is because for a non-transitive action, either the <a href="Orbit_(group_theory)" class="mw-redirect" title="Orbit (group theory)">orbits</a> of <i>G</i> form a nontrivial partition preserved by <i>G</i>, or the group action is trivial, in which case <i>all</i> nontrivial partitions of <i>X</i> (which exists for |<i>X</i>| ≥ 3) are preserved by <i>G</i>.
</p><p>This terminology was introduced by <a href="%C3%89variste_Galois" title="Évariste Galois">Évariste Galois</a> in his last letter, in which he used the French term <i>équation primitive</i> for an equation whose <a href="Galois_group" title="Galois group">Galois group</a> is primitive.<sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup>
</p>
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<div class="mw-heading mw-heading2"><h2 id="Properties">Properties</h2></div><p>
In the same letter in which he introduced the term "primitive", Galois stated the following theorem:<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup></p><blockquote><p>If <i>G</i> is a primitive <a href="Solvable_group" title="Solvable group">solvable group</a> acting on a finite set <i>X</i>, then the order of <i>X</i> is a power of a <a href="Prime_number" title="Prime number">prime number</a> <i>p</i>. Further, <i>X</i> may be identified with an <a href="Affine_space" title="Affine space">affine space</a> over the <a href="Finite_field" title="Finite field">finite field</a> with <i>p</i> elements, and <i>G</i> acts on <i>X</i> as a subgroup of the <a href="Affine_group" title="Affine group">affine group</a>.</p></blockquote><p>If the set <i>X</i> on which <i>G</i> acts is finite, its cardinality is called the <i>degree</i> of <i>G</i>.
</p><p>A corollary of this result of Galois is that, if <span class="texhtml mvar" style="font-style:italic;">p</span> is an odd prime number, then the order of a solvable transitive group of degree <span class="texhtml mvar" style="font-style:italic;">p</span> is a divisor of <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p(p-1).}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>p</mi>
<mo stretchy="false">(</mo>
<mi>p</mi>
<mo>−<!-- − --></mo>
<mn>1</mn>
<mo stretchy="false">)</mo>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle p(p-1).}</annotation>
</semantics>
</math></span><img src="./bc7d8799913b9dd4aeb920e71ef64b35cc1b600e.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; margin-left: -0.089ex; width:8.887ex; height:2.843ex;" alt="{\displaystyle p(p-1).}" loading="lazy"></span> In fact, every transitive group of prime degree is primitive (since the number of elements of a partition fixed by <span class="texhtml mvar" style="font-style:italic;">G</span> must be a divisor of <span class="texhtml mvar" style="font-style:italic;">p</span>), and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p(p-1)}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>p</mi>
<mo stretchy="false">(</mo>
<mi>p</mi>
<mo>−<!-- − --></mo>
<mn>1</mn>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle p(p-1)}</annotation>
</semantics>
</math></span><img src="./cff815284a731edb3a54121e8c45b6bd66f8c650.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; margin-left: -0.089ex; width:8.24ex; height:2.843ex;" alt="{\displaystyle p(p-1)}" loading="lazy"></span> is the cardinality of the affine group of an affine space with <span class="texhtml mvar" style="font-style:italic;">p</span> elements.
</p><p>It follows that, if <span class="texhtml mvar" style="font-style:italic;">p</span> is a prime number greater than 3, the <a href="Symmetric_group" title="Symmetric group">symmetric group</a> and the <a href="Alternating_group" title="Alternating group">alternating group</a> of degree <span class="texhtml mvar" style="font-style:italic;">p</span> are not solvable, since their order are greater than <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle p(p-1).}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>p</mi>
<mo stretchy="false">(</mo>
<mi>p</mi>
<mo>−<!-- − --></mo>
<mn>1</mn>
<mo stretchy="false">)</mo>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle p(p-1).}</annotation>
</semantics>
</math></span><img src="./bc7d8799913b9dd4aeb920e71ef64b35cc1b600e.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; margin-left: -0.089ex; width:8.887ex; height:2.843ex;" alt="{\displaystyle p(p-1).}" loading="lazy"></span> <a href="Abel%E2%80%93Ruffini_theorem" title="Abel–Ruffini theorem">Abel–Ruffini theorem</a> results from this and the fact that there are polynomials with a symmetric Galois group.
</p><p>An equivalent definition of primitivity relies on the fact that every transitive action of a group <i>G</i> is isomorphic to an action arising from the canonical action of <i>G</i> on the set <i>G</i>/<i>H</i> of <a href="Coset" title="Coset">cosets</a> for <i>H</i> a subgroup of <i>G</i>. A group action is primitive if it is isomorphic to <i>G</i>/<i>H</i> for a <a href="Maximal_subgroup" title="Maximal subgroup"><i>maximal</i> subgroup</a> <i>H</i> of <i>G</i>, and imprimitive otherwise (that is, if there is a proper subgroup <i>K</i> of <i>G</i> of which <i>H</i> is a proper subgroup). These imprimitive actions are examples of <a href="Induced_representation" title="Induced representation">induced representations</a>.
</p><p>The numbers of primitive groups of small degree were stated by <a href="Robert_Carmichael" class="mw-redirect" title="Robert Carmichael">Robert Carmichael</a> in 1937:
</p>
<table class="wikitable">
<tbody><tr>
<td>Degree</td>
<td>2</td>
<td>3</td>
<td>4</td>
<td>5</td>
<td>6</td>
<td>7</td>
<td>8</td>
<td>9</td>
<td>10</td>
<td>11</td>
<td>12</td>
<td>13</td>
<td>14</td>
<td>15</td>
<td>16</td>
<td>17</td>
<td>18</td>
<td>19</td>
<td>20</td>
<td>21</td>
<td>22</td>
<td>23</td>
<td>24</td>
<td><a href="OEIS" class="mw-redirect" title="OEIS">OEIS</a>
</td></tr>
<tr>
<td>Number</td>
<td>1</td>
<td>2</td>
<td>2</td>
<td>5</td>
<td>4</td>
<td>7</td>
<td>7</td>
<td>11</td>
<td>9</td>
<td>8</td>
<td>6</td>
<td>9</td>
<td>4</td>
<td>6</td>
<td>22</td>
<td>10</td>
<td>4</td>
<td>8</td>
<td>4</td>
<td>9</td>
<td>4</td>
<td>7</td>
<td>5</td>
<td><a href="https://oeis.org/A000019" class="extiw external" title="oeis:A000019">A000019</a>
</td></tr></tbody></table>
<p>There are a large number of primitive groups of degree 16. As Carmichael notes, all of these groups, except for the <a href="Symmetric_group" title="Symmetric group">symmetric</a> and <a href="Alternating_group" title="Alternating group">alternating</a> group, are subgroups of the <a href="Affine_group" title="Affine group">affine group</a> on the 4-dimensional space over the 2-element <a href="Finite_field" title="Finite field">finite field</a>.
</p>
<div class="mw-heading mw-heading2"><h2 id="Examples">Examples</h2></div>
<ul><li>Consider the <a href="Symmetric_group" title="Symmetric group">symmetric group</a> <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S_{3}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>S</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>3</mn>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle S_{3}}</annotation>
</semantics>
</math></span><img src="./70e15f3e200aaa247f69c43110cc5a09ecc91b89.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.479ex; height:2.509ex;" alt="{\displaystyle S_{3}}" loading="lazy"></span> acting on the set <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle X=\{1,2,3\}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>X</mi>
<mo>=</mo>
<mo fence="false" stretchy="false">{</mo>
<mn>1</mn>
<mo>,</mo>
<mn>2</mn>
<mo>,</mo>
<mn>3</mn>
<mo fence="false" stretchy="false">}</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle X=\{1,2,3\}}</annotation>
</semantics>
</math></span><img src="./955caac5ab925f254a1926536391241bb76f56e6.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:12.959ex; height:2.843ex;" alt="{\displaystyle X=\{1,2,3\}}" loading="lazy"></span> and the permutation</li></ul>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \eta ={\begin{pmatrix}1&2&3\\2&3&1\end{pmatrix}}.}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>η<!-- η --></mi>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mrow>
<mo>(</mo>
<mtable rowspacing="4pt" columnspacing="1em">
<mtr>
<mtd>
<mn>1</mn>
</mtd>
<mtd>
<mn>2</mn>
</mtd>
<mtd>
<mn>3</mn>
</mtd>
</mtr>
<mtr>
<mtd>
<mn>2</mn>
</mtd>
<mtd>
<mn>3</mn>
</mtd>
<mtd>
<mn>1</mn>
</mtd>
</mtr>
</mtable>
<mo>)</mo>
</mrow>
</mrow>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \eta ={\begin{pmatrix}1&2&3\\2&3&1\end{pmatrix}}.}</annotation>
</semantics>
</math></span><img src="./f7963ee7208a0aa79180829605eb7d6203345f7a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:17.22ex; height:6.176ex;" alt="{\displaystyle \eta ={\begin{pmatrix}1&2&3\\2&3&1\end{pmatrix}}.}" loading="lazy"></span></dd></dl>
<p>Both <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S_{3}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>S</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>3</mn>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle S_{3}}</annotation>
</semantics>
</math></span><img src="./70e15f3e200aaa247f69c43110cc5a09ecc91b89.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.479ex; height:2.509ex;" alt="{\displaystyle S_{3}}" loading="lazy"></span> and the group generated by <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \eta }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>η<!-- η --></mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \eta }</annotation>
</semantics>
</math></span><img src="./e4d701857cf5fbec133eebaf94deadf722537f64.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:1.169ex; height:2.176ex;" alt="{\displaystyle \eta }" loading="lazy"></span> are primitive.
</p>
<ul><li>Now consider the <a href="Symmetric_group" title="Symmetric group">symmetric group</a> <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S_{4}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<msub>
<mi>S</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>4</mn>
</mrow>
</msub>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle S_{4}}</annotation>
</semantics>
</math></span><img src="./fc1632bc1d95d33ccb5473b9d8cc333c2dd0d13a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.479ex; height:2.509ex;" alt="{\displaystyle S_{4}}" loading="lazy"></span> acting on the set <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{1,2,3,4\}}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo fence="false" stretchy="false">{</mo>
<mn>1</mn>
<mo>,</mo>
<mn>2</mn>
<mo>,</mo>
<mn>3</mn>
<mo>,</mo>
<mn>4</mn>
<mo fence="false" stretchy="false">}</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \{1,2,3,4\}}</annotation>
</semantics>
</math></span><img src="./ebf4ca66fd59843b349aed8ffa7655c1aae77625.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:10.077ex; height:2.843ex;" alt="{\displaystyle \{1,2,3,4\}}" loading="lazy"></span> and the permutation</li></ul>
<dl><dd><span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \sigma ={\begin{pmatrix}1&2&3&4\\2&3&4&1\end{pmatrix}}.}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>σ<!-- σ --></mi>
<mo>=</mo>
<mrow class="MJX-TeXAtom-ORD">
<mrow>
<mo>(</mo>
<mtable rowspacing="4pt" columnspacing="1em">
<mtr>
<mtd>
<mn>1</mn>
</mtd>
<mtd>
<mn>2</mn>
</mtd>
<mtd>
<mn>3</mn>
</mtd>
<mtd>
<mn>4</mn>
</mtd>
</mtr>
<mtr>
<mtd>
<mn>2</mn>
</mtd>
<mtd>
<mn>3</mn>
</mtd>
<mtd>
<mn>4</mn>
</mtd>
<mtd>
<mn>1</mn>
</mtd>
</mtr>
</mtable>
<mo>)</mo>
</mrow>
</mrow>
<mo>.</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \sigma ={\begin{pmatrix}1&2&3&4\\2&3&4&1\end{pmatrix}}.}</annotation>
</semantics>
</math></span><img src="./a545243dc81a7959b66c86c8638d79ff31605b0a.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -2.505ex; width:20.865ex; height:6.176ex;" alt="{\displaystyle \sigma ={\begin{pmatrix}1&2&3&4\\2&3&4&1\end{pmatrix}}.}" loading="lazy"></span></dd></dl>
<p>The group generated by <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \sigma }">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>σ<!-- σ --></mi>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle \sigma }</annotation>
</semantics>
</math></span><img src="./59f59b7c3e6fdb1d0365a494b81fb9a696138c36.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.33ex; height:1.676ex;" alt="{\displaystyle \sigma }" loading="lazy"></span> is not primitive, since the partition <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle (X_{1},X_{2})}">
<semantics>
<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mo stretchy="false">(</mo>
<msub>
<mi>X</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>1</mn>
</mrow>
</msub>
<mo>,</mo>
<msub>
<mi>X</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>2</mn>
</mrow>
</msub>
<mo stretchy="false">)</mo>
</mstyle>
</mrow>
<annotation encoding="application/x-tex">{\displaystyle (X_{1},X_{2})}</annotation>
</semantics>
</math></span><img src="./60ba8ba324660a77a8647ecd53c689536879fe58.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:8.8ex; height:2.843ex;" alt="{\displaystyle (X_{1},X_{2})}" loading="lazy"></span> where <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle X_{1}=\{1,3\}}">
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<annotation encoding="application/x-tex">{\displaystyle X_{1}=\{1,3\}}</annotation>
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</math></span><img src="./e6710432ccca02acd5d7cf5f2aa39c3b7c899cf4.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:11.761ex; height:2.843ex;" alt="{\displaystyle X_{1}=\{1,3\}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle X_{2}=\{2,4\}}">
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<mi>X</mi>
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<annotation encoding="application/x-tex">{\displaystyle X_{2}=\{2,4\}}</annotation>
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</math></span><img src="./88d82e7dc75ccd97ec06f77be659437454b87a8d.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:11.761ex; height:2.843ex;" alt="{\displaystyle X_{2}=\{2,4\}}" loading="lazy"></span> is preserved under <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \sigma }">
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</math></span><img src="./59f59b7c3e6fdb1d0365a494b81fb9a696138c36.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.338ex; width:1.33ex; height:1.676ex;" alt="{\displaystyle \sigma }" loading="lazy"></span>, i.e. <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \sigma (X_{1})=X_{2}}">
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<mrow class="MJX-TeXAtom-ORD">
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<mi>σ<!-- σ --></mi>
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<mn>2</mn>
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<annotation encoding="application/x-tex">{\displaystyle \sigma (X_{1})=X_{2}}</annotation>
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</math></span><img src="./60bd54d86bae4d983f6f928cad930073fa023793.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:12.194ex; height:2.843ex;" alt="{\displaystyle \sigma (X_{1})=X_{2}}" loading="lazy"></span> and <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \sigma (X_{2})=X_{1}}">
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<mrow class="MJX-TeXAtom-ORD">
<mstyle displaystyle="true" scriptlevel="0">
<mi>σ<!-- σ --></mi>
<mo stretchy="false">(</mo>
<msub>
<mi>X</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>2</mn>
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<mi>X</mi>
<mrow class="MJX-TeXAtom-ORD">
<mn>1</mn>
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</mrow>
<annotation encoding="application/x-tex">{\displaystyle \sigma (X_{2})=X_{1}}</annotation>
</semantics>
</math></span><img src="./a242c8722fcc4ff1ddef07f8053b53f5dd9c83b4.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:12.194ex; height:2.843ex;" alt="{\displaystyle \sigma (X_{2})=X_{1}}" loading="lazy"></span>.
</p>
<ul><li>Every transitive group of prime degree is primitive</li>
<li>The <a href="Symmetric_group" title="Symmetric group">symmetric group</a> <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle S_{n}}">
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<annotation encoding="application/x-tex">{\displaystyle S_{n}}</annotation>
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<annotation encoding="application/x-tex">{\displaystyle \{1,\ldots ,n\}}</annotation>
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</math></span><img src="./730f6906700685b6d52f3958b1c2ae659d2d97d2.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.671ex; width:2.962ex; height:2.509ex;" alt="{\displaystyle A_{n}}" loading="lazy"></span> acting on the set <span class="mwe-math-element mwe-math-element-inline"><span class="mwe-math-mathml-inline mwe-math-mathml-a11y" style="display: none;"><math xmlns="http://www.w3.org/1998/Math/MathML" alttext="{\displaystyle \{1,\ldots ,n\}}">
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<annotation encoding="application/x-tex">{\displaystyle \{1,\ldots ,n\}}</annotation>
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</math></span><img src="./0401c38cf1a2e51b30b38f4b93b5285aa77f8fad.svg" class="mwe-math-fallback-image-inline mw-invert skin-invert" aria-hidden="true" style="vertical-align: -0.838ex; width:10.06ex; height:2.843ex;" alt="{\displaystyle \{1,\ldots ,n\}}" loading="lazy"></span> is primitive for every <i>n</i> > 2.</li></ul>
<div class="mw-heading mw-heading2"><h2 id="See_also">See also</h2></div>
<ul><li><a href="Block_(permutation_group_theory)" title="Block (permutation group theory)">Block (permutation group theory)</a></li>
<li><a href="Jordan's_theorem_(symmetric_group)" title="Jordan's theorem (symmetric group)">Jordan's theorem (symmetric group)</a></li>
<li><a href="O'Nan%E2%80%93Scott_theorem" title="O'Nan–Scott theorem">O'Nan–Scott theorem</a>, a classification of finite primitive groups into various types</li></ul>
<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>
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<div class="mw-references-wrap"><ol class="references">
<li id="cite_note-1"><span class="mw-cite-backlink"><b><a href="#cite_ref-1">^</a></b></span> <span class="reference-text"> Galois' last letter: <a rel="nofollow" class="external free" href="http://www.galois.ihp.fr/ressources/vie-et-oeuvre-de-galois/lettres/lettre-testament">http://www.galois.ihp.fr/ressources/vie-et-oeuvre-de-galois/lettres/lettre-testament</a></span>
</li>
<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text">Galois used a different terminology, because most of the terminology in this statement was introduced afterwards, partly for clarifying the concepts introduced by Galois.</span>
</li>
</ol></div></div>
<ul><li><a href="Colva_Roney-Dougal" title="Colva Roney-Dougal">Roney-Dougal, Colva M.</a> <i>The primitive permutation groups of degree less than 2500</i>, <a href="Journal_of_Algebra" title="Journal of Algebra">Journal of Algebra</a> 292 (2005), no. 1, 154–183.</li>
<li>The <a rel="nofollow" class="external text" href="http://www.gap-system.org">GAP</a> <a rel="nofollow" class="external text" href="http://www.gap-system.org/Datalib/prim.html">Data Library "Primitive Permutation Groups"</a>.</li>
<li>Carmichael, Robert D., <i>Introduction to the Theory of Groups of Finite Order.</i> Ginn, Boston, 1937. Reprinted by Dover Publications, New York, 1956.</li>
<li><span class="citation mathworld" id="Reference-Mathworld-Primitive_Group_Action"><style data-mw-deduplicate="TemplateStyles:r1238218222">
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.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}
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</style><cite id="CITEREFWeisstein" class="citation web cs1">Todd Rowland. <a rel="nofollow" class="external text" href="https://mathworld.wolfram.com/PrimitiveGroupAction.html">"Primitive Group Action"</a>. <i><a href="MathWorld" title="MathWorld">MathWorld</a></i>.</cite></span></li></ul></div><!--htdig_noindex--><div><div class="zim-footer">
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