Category Archives: symmetric group

one of my favourite mathematical objects

Chains of semigroups

I have written here about the lovely formula for the length of the longest chain of subgroups in the symmetric group Sn: take n, increase it by 50% (rounding up if necessary), subtract the number of ones in the base … Continue reading

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Remoteness

After the last bit of bureaucratic nonsense, what a relief to turn to mathematics again. Maximilien Gadouleau and I have just submitted a paper about a concept for finite metric spaces somewhat related to domination, which we call remoteness. It … Continue reading

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The symmetric group, 12

This instalment is about the maximal subgroups of the symmetric group, and the O’Nan–Scott Theorem. There are two versions of this theorem, one of which is sometimes called the Aschbacher–O’Nan–Scott Theorem. One is about maximal subgroups of the symmetric group … Continue reading

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The symmetric group, 11

I am going to talk about a celebrated theorem of John Dixon and some of its variants; this is on my mind at the moment, for reasons I will explain at the end. Dixon’s theorem is easily stated. Two random … Continue reading

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The symmetric group, 9

There are many different ways to regard a finite symmetric group as a metric space. These have been used for various purposes. Here I would like to say something about them. One application of such metrics is in non-parametric statistics. … Continue reading

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The symmetric group, 6

I quote here the review on MathSciNet for a paper which appeared in a conference proceedings in 1970. (This review, of course, was published in Mathematical Reviews, and now has been put on the website.) I have made one correction, … Continue reading

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The symmetric group, 5

Time to say a bit about the combinatorics of the symmetric group. Certainly not a complete survey of a vast topic, which would be quite impossible; I will touch on just a few things. Loosely speaking, the subject divides into … Continue reading

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