Author Archives: Peter Cameron

About Peter Cameron

I count all the things that need to be counted.

Scottish Combinatorics Conference

Posted on 28/05/2023 by Peter Cameron

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 →

Posted in events, mathematics | Tagged , , , , , , | 5 Comments

London Combinatorics Colloquia 2023

Posted on 17/05/2023 by Peter Cameron

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 →

Posted in events, exposition | Tagged , , , , , , , , , | 3 Comments

John Bullough

Posted on 16/05/2023 by Peter Cameron

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 →

Posted in Uncategorized | Tagged , | 2 Comments

Bases

Posted on 15/04/2023 by Peter Cameron

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 →

Posted in doing mathematics, exposition | Tagged , , , , | Leave a comment

Orthogonal block structures

Posted on 09/04/2023 by Peter Cameron

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 →

Posted in doing mathematics, exposition | Tagged , , , | 1 Comment

George F. Simmons

Posted on 25/03/2023 by Peter Cameron

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 →

Posted in books | Tagged , , | 2 Comments

New web address

Posted on 17/03/2023 by Peter Cameron

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 →

Posted in the Web | Tagged | 5 Comments

Birthday conferences

Posted on 13/03/2023 by Peter Cameron

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 →

Posted in doing mathematics, events | Tagged , , , , , | Leave a comment

Between transitive and primitive

Posted on 09/03/2023 by Peter Cameron

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 →

Posted in doing mathematics, exposition | Tagged , , , | Leave a comment

An exercise in number theory

Posted on 17/02/2023 by Peter Cameron

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 →

Posted in doing mathematics, open problems | Tagged , | 6 Comments