Difference between revisions of "Alternating group"

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The '''alternating group''' on a [[finite]] [[set]] <math>M</math> is the [[group]] of [[symmetric group | even permutations]] on the set <math>M</math>; it is denoted <math>A_M</math>, <math>\mathfrak{A}_M</math>, or <math>\text{Alt}(M)</math>.  When <math>M = \{1, \dotsc, n\}</math>, this group is denoted <math>A_n</math>, <math>\mathfrak{A}_n</math>, or <math>\text{Alt}(n)</math>.  This is a [[normal subgroup]] of the [[symmetric group]]; and for <math>n=3</math> or <math>n\ge 5</math>, it is in fact a [[simple group]].
 
The '''alternating group''' on a [[finite]] [[set]] <math>M</math> is the [[group]] of [[symmetric group | even permutations]] on the set <math>M</math>; it is denoted <math>A_M</math>, <math>\mathfrak{A}_M</math>, or <math>\text{Alt}(M)</math>.  When <math>M = \{1, \dotsc, n\}</math>, this group is denoted <math>A_n</math>, <math>\mathfrak{A}_n</math>, or <math>\text{Alt}(n)</math>.  This is a [[normal subgroup]] of the [[symmetric group]]; and for <math>n=3</math> or <math>n\ge 5</math>, it is in fact a [[simple group]].
  
<math>A_n</math> is also the group of determinant-preserving permutations of the rows of an <math>n \times n</math> [[matrix]].
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<math>A_n</math> is also the group of [[determinant]]-preserving permutations of the rows of an <math>n \times n</math> [[matrix]].
  
 
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Latest revision as of 10:47, 4 March 2022

The alternating group on a finite set $M$ is the group of even permutations on the set $M$; it is denoted $A_M$, $\mathfrak{A}_M$, or $\text{Alt}(M)$. When $M = \{1, \dotsc, n\}$, this group is denoted $A_n$, $\mathfrak{A}_n$, or $\text{Alt}(n)$. This is a normal subgroup of the symmetric group; and for $n=3$ or $n\ge 5$, it is in fact a simple group.

$A_n$ is also the group of determinant-preserving permutations of the rows of an $n \times n$ matrix.

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See also