Banff, days 4 and 5

The problem session was actually on day 3, but I already talked about it. The most interesting problems to me were the ones I stated in the preceding post.

The next morning there was 5 or 10 centimetres of snow, and more was coming down; I was nearly eaten by a snowplough on the way to breakfast. But by lunchtime, the snow had stopped and the trees and roofs were beginning to shed their loads onto the ground or unsuspecting pedestrians below.

The best of the morning session for me was Greg Cherlin’s talk. He has done more than anyone on the classification of homogeneous relational structures. He talked about the classification, concentrating on directed graphs, ordered graphs, and graphs as metric spaces. (All of these are binary relational structures; going beyond binary seems very difficult.) A characteristic of Greg’s talks is that they are not full of theorems, but instead take a lot of trouble getting across the essential ideas that go into the proof: potentially very valuable, but you have to work! Of course, ordered graphs are very relevant for the Ramsey theory/topological dynamics connection which has turned out to be relevant for CSP.

Yesterday, Jarik Nešetřil had told me that Raymond Paley is buried in Banff cemetery; he was killed by an avalanche while ski-ing near Banff. I decided to use the lunch break to look for the grave. It was not easy going; the cemetery is just below BIRS, but it was lying under deep snow. But I did a random walk, and just before I was tempted to give up I found it:

Paley's grave

The main talk in the afternoon was by Ralph McKenzie. He didn’t use slides, but wrote small on the board, and the lighting was not really adequate. But BIRS has live streaming of lectures; I found I could watch on my laptop and see clearly what he was writing, and hear his voice without needing to put the sound on. Technological overkill!

Day 5 was departure day. Unfortunately I had to leave early; I had not been able to get a direct evening flight to London from Calgary, but had to take a day flight to Vancouver and change there. More possibility for something to go wrong … I very much regretted having to miss Manuel Bodirsky’s talk. But by the time I got to Calgary the slides were on the conference web page. (The system for posting slides was brilliant: what looked like another device on tle lecture room computer desktop was really the conference web page, and any file dragged there was automatically posted.) I took a look at the slides but decided to leave studying them until I am somewhere that battery life is not a problem.

About Peter Cameron

I count all the things that need to be counted.
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