Category Archives: exposition

a post aimed to teach something

NBSAN in St Andrews

This week, during a spell of lovely spring weather and new blossom, the 20th meeting of the North British Semigroups and Applications Network was held in St Andrews, organised by Markus Pfeiffer. It was good to see old friends such … Continue reading

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Generating singular maps

Last week, Max Gadouleau and Alonso Castillo-Ramirez visited St Andrews. With James Mitchell, we worked on a problem about generating the semigroup of singular maps on a set (the full transformation semigroup minus the symmetric group). As usual in this … Continue reading

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Jack Edmonds: the London gigs

Jack Edmonds is a larger-than-life figure in the world of combinatorial optimization and polyhedral combinatorics. If you are a student, you really should grasp this chance to meet him! More than fifty years ago, Jack was perhaps the first person … Continue reading

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A paper on synchronization

A paper on synchronization, written with João Araújo, Wolfram Bentz, Gordon Royle and Artur Schaefer, has just appeared on the arXiv. It is quite a substantial paper, and goes well beyond anything we have published (or that I have written … Continue reading

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Representing the Fano matroid

In my lecture today I proved that the Fano matroid is representable over a field F if and only the characteristic of F is 2. There is a proof of this using only the classical theorems of Ceva and Menelaus … Continue reading

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1247

Yesterday my colleague Collin Bleak sent me an email containing the number 1247. I will explain why this made me so pleased. Automata Our problem concerns automata. If you know Collin, you may suspect that it has something to do … Continue reading

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The combinatorial hierarchy

Following up a conversation with John Amson at Rufflets Hotel, just outside St Andrews, I was led to a paper on combinatorial physics: Ted Bastin, H. Pierre Noyes, John Amson, Clive W. Kilmister: On the physical interpretation and the mathematical … Continue reading

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