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# Tag Archives: permutations

## Permutation patterns, days 3-5

I never promised to write something every day … Anyway, the conference is now over. The LMS conference wi-fi was just not up to the demands of a conference big enough to fill the Hardy room, so lots of on-line … Continue reading

Posted in events
Tagged Fox's theorem, genetics, Marcus-Tardos theorem, permutations, Peter Sellers, stacks, Stanley Kubrick, Stanley-Wilf conjecture
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## Equivalence relations, 2

I believe, and have said in earlier posts here and here on this blog, that the Equivalence Relation Theorem is the modern pons asinorum, the bridge which you must cross in order to become a mathematician: it is essential to … Continue reading

Posted in doing mathematics
Tagged acyclic orientations, equivalence relations, Moebius inversion, permutations
7 Comments

## OuLiPo

OuLiPo, or Ouvroir de Littérature Potentielle (which they translate as “Charity bazaar of potential literature”) were a collection of writers I knew little about until yesterday. I knew a couple of things: Martin Gardner wrote about them, mentioning among other … Continue reading

Posted in mathematics and ...
Tagged Claude Berge, combinations, games, Georges Perec, graphs, groups, literature, orthogonal Latin squares, permutations, Pierre Rosenstiehl
3 Comments

## Bijective proofs

A fourth proof Last month I described three proofs of the formula for the number of ways to choose k objects from a set of n, if repetition is allowed and order is not significant; it is the same as … Continue reading

Posted in exposition, open problems
Tagged bijections, Catalan numbers, Catalan objects, Dima Fon-Der-Flaass, permutations, sampling
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## Busy times, 4

I meant to finish up the last item with a comment on the relationship between teaching and examining. I have never regarded examining as more than a necessary evil for teachers. So many times, while I was marking the scripts, … Continue reading