Category Archives: exposition

a post aimed to teach something

Polynomially bounded orbit counts

The best news I had yesterday was an email from Justine Falque with a link to a paper that she and Nicolas Thiéry have just put on the arXiv. The 12-page document is only the “short version”, and a longer … Continue reading

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Integrals of groups

Everyone who has studied mathematics knows what the derivative and integral of a function are. The derivative measures rate of change, the integral (the inverse operation) measures area under a curve. They are inverse operations; and two functions have the … Continue reading

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A counting problem

I quite often get questions by email. Mostly I can’t answer them, but sometimes I can, and sometimes the answers might be of more general interest. Suppose that we have m boxes and a supply of identical balls. In how … Continue reading

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A new kind of design?

Rosemary and I have just put on the arXiv a paper prompted by a question by Valery Fedorov. Suppose that we are testing a number v1 of drugs on a number v2 of cancer types. To simplify the protocol, at … Continue reading

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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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