Category Archives: exposition

a post aimed to teach something

Symmetry vs Regularity

This is the title of a conference to be held next year (2018) from 1 to 7 July, in Pilsen, Bohemia, Czech Republic. The subtitle is “The first 50 years since Weisfeiler-Leman stabilization”, and the webpage is here. If you … Continue reading

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Workshop on Bannai-Ito theory

The original purpose of our trip to China was to speak at an international workshop on Bannai-Ito theory at Zhejiang University in Hangzhou, a popular Chinese tourist destination. Hangzhou is set on an artificial (but centuries old) lake, with islands, … Continue reading

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Shrikhande 100

Professor S. S. Shrikhande is 100. I offer him my warmest congratulations and birthday greetings. Among much else in his distinguished career, he was one of the three who showed that a pair of orthogonal Latin squares exists for every … Continue reading

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Synchronization and all that, 2

The story I told in the last post is not over. The recent development is that we spotted a mistake in the paper. An easy mistake to make: we had simply used the symbol n in two different places with … Continue reading

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EKR, Steiner systems, association schemes, and all that

A great number of mathematical problems amount to looking in a large but highly structured graph, and finding a complete or null subgraph of largest possible size there. For a simple example, consider Latin squares of order n. One of … Continue reading

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p-values, 2

In this sequel, I want to tell a story which perhaps indicates that the philosophical positions of scientists and statisticians have less influence on what really goes on than much more practical things like publication policies of journals. This story … Continue reading

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The random graph and anti-foundation

Last year, Bea Adam-Day, one of my undergraduate project students, settled a question that had been bugging me for years. According to the downward Löwenheim–Skolem Theorem of first-order logic (a consequence of the proof of Gödel’s Completeness Theorem), if a … Continue reading

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