Author Archives: Peter Cameron

About Peter Cameron

I count all the things that need to be counted.

Scottish Combinatorics Conference

Another event back in face-to-face mode, the Scottish Combinatorics Conference took place this week at the University of Strathclyde in Glasgow, organised by David Bevan and other members of the combinatorics group. Glasgow is a bus ride from St Andrews, … Continue reading

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London Combinatorics Colloquia 2023

In London last week for this (usually) annual event, now happily back live. In contrast to usual practice, I will discuss the second day first. Norman Biggs was the founder of the combinatorics group at the London School of Economics, … Continue reading

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John Bullough

I never met John Bullough, and had never heard of him until his death was reported a few days ago. But I owe him a great debt. He founded the Scottish Charity Air Ambulance. After Rosemary fell into the Kenly … Continue reading

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A base for a permutation group is a sequence (a1,…,ar) of points in the permutation domain whose pointwise stabiliser is the identity. Bases were introduced in computational group theory by Charles Sims, since two elements of a permutation group are … Continue reading

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Orthogonal block structures

If you google “commuting equivalence relations” you will find signs of a large and rich literature. I want to talk about one aspect, on the border of algebraic combinatorics and experimental design: orthogonal block structures. Look up orthogonal block structures … Continue reading

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George F. Simmons

Browsing a back issue of the BSHM bulletin, I found a review of the book Calculus Gems by George F. Simmons, from which I learned that he died in 2019 at the age of 94. I never met Simmons, and … Continue reading

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New web address

Thanks to all of you who made suggestions about moving my webpages, since the University will take the old ones down at the end of the month. GitHub was the most popular suggestion, so I went with that. The new … Continue reading

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Birthday conferences

The impending removal of my university web pages has led me to put here the slides of some talks. I have been extremely fortunate in having wonderful colleagues who have organised three birthday conferences for me. (Well, one was actually … Continue reading

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Between transitive and primitive

Many familiar properties of permutation groups form a hierarchy. A few years ago, with João Araújo and Ben Steinberg, I wrote a survey on properties related to synchronization of finite automota, lying between primitivity and 2-transitivity. Here is a new … Continue reading

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An exercise in number theory

Here is a cute little problem which I can’t solve. I thought I needed the answer but it turned out that I didn’t, so as far as I know there is no application. Let n = p1a1…psas, where the pi are distinct … Continue reading

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