Category Archives: exposition

a post aimed to teach something

Normal

There are various overused terms in mathematics. “Normal” is one of them. Perhaps the four commonest uses are the following: A complex square matrix is normal if it commutes with its conjugate transpose. Normal matrices are precisely the ones which … Continue reading

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Synchronization update

There is some recent news about the synchronization project. Two steps forward have occurred. The set-up Here is a brief recapitulation. Let G be a transitive permutation group on Ω, where |Ω| = n. We say that G is non-synchronizing if there … Continue reading

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A mathematical promenade

I haven’t posted for a while; I have been in China where the firewall allows me to read WordPress but not to post. Normal service now resumed (hopefully). Given four real polynomials, all of which vanish at the origin, suppose … Continue reading

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Dugald Macpherson’s birthday meeting

Still catching up on the backlog: last week I was in Edinburgh for a meeting at ICMS for Dugald Macpherson’s birthday. The ICMS has just moved to new premises at the top of the University of Edinburgh’s new Bayes Centre, … Continue reading

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The existential transversal property

One of the first things that João Araújo introduced me to when we started collaborating, after synchronization, was the universal transversal property: a permutation group G on the set {1,…,n} has the k-universal transversal property (k-ut for short) if, given … Continue reading

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The infinite lottery

Probability is a mathematical subject where the application of the results to the real world remains controversial, and different schools of thought flourish. Littlewood, in his Miscellany, discusses this, and comes firmly to the conclusion that probability theory can say … Continue reading

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Scottish Combinatorics Meeting 2018

Last week saw the fourth annual Scottish Combinatorial Meeting in Edinburgh, in the Informatics Forum at the University of Edinburgh. The building was new to me, but easy enough to find, and having a terrace with a fine view of … Continue reading

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