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# Category Archives: exposition

## Conventions

I woke this morning thinking about something I learned in physics at school. A wire carrying a current in a magnetic field is acted on by a force (if it is not parallel to the field): in what direction does … Continue reading

## There is no McLaughlin geometry

Congratulations to Patric Östergård and Leonard Soicher, who have just completed a big computation whose conclusion is “There is no McLaughlin geometry”. The run-time of the computation was about 250 core-years. So what did they compute, and why does it … Continue reading

## Private information retrieval

Yesterday I was at a meeting on this subject at Royal Holloway, organised by Simon Blackburn. The subject is relatively young; it began in 1995 with a paper by Chor, Goldreich, Kushilevitz and Sudan. At the meeting, Alex Vardy gave … Continue reading

## An LTCC book

The Taught Course Centres for PhD students in the Mathematical Sciences were set up as the result of a recommendation of the last-but-one International Review of Mathematics. The review panel said that the highly specialised nature of British PhDs meant … Continue reading

## The Higman–Thompson groups

I celebrated the last day of spring last week with the appearance of two substantial papers on the arXiv: one with Maria Elisa Fernandes, Dimitri Leemans, and Mark Mixer, proving that the maximum rank of a regular polytope whose group … Continue reading

Posted in exposition
Tagged automata, Cantor space, Grtaham Higman, homeomorphisms, regular polytopes, Richard Thompson, synchronization, transducers
3 Comments

## Permutation groups in Bristol

On 1 June, a meeting of the “Groups and Applications” triangle was held in Bristol. (This peripatetic meeting was a long thin triangle with vertices London, Birmingham and Manchester, but with the inclusion of Bristol it is not clear what … Continue reading

## Peter Keevash at IMS

This picture (courtesy of Sebi Cioabă) shows Peter Keevash with the diagram which illustrates the proof strategy for his theorem. Perhaps it will be helpful, especially to those who heard the lecture (or similar lectures elsewhere). Thanks Sebi!