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arXiv · 1705.06651

z-Classes and Rational Conjugacy Classes in Alternating Groups

Sushil Bhunia·Dilpreet Kaur·Anupam Singh
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Abstract

In this paper, we compute the number of z-classes (conjugacy classes of centralizers of elements) in the symmetric group S_n, when n is greater or equal to 3 and alternating group A_n, when n is greater or equal to 4. It turns out that the difference between the number of conjugacy classes and the number of z-classes for S_n is determined by those restricted partitions of n-2 in which 1 and 2 do not appear as its part. And, in the case of alternating groups, it is determined by those restricted partitions of n-3 which has all its parts distinct, odd and in which 1 (and 2) does not appear as its part, along with an error term. The error term is given by those partitions of n which have each of its part distinct, odd and perfect square. Further, we prove that the number of rational-valued irreducible complex characters for A_n is same as the number of conjugacy classes which are rational.

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Sushil Bhunia, Dilpreet Kaur, Anupam Singh. 2017-05-18. z-Classes and Rational Conjugacy Classes in Alternating Groups. https://arxiv.org/abs/1705.06651

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