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Category Archives: Combinatorics
Herstmonceux
As I mentioned, after Vancouver I went to a conference at Herstmonceux Castle in Sussex, England. It was mathematically excellent, and I feel that BBC detective shows properly prepared me for my first visit to the UK. Trees in England … Continue reading
Posted in Academia, Combinatorics, Math, Trees
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The Erdős FBI file
A cute little article here about Paul Erdős’s FBI file. The short version is … that it’s not very interesting; the FBI routinely (and correctly) determined that he was just interested in doing mathematics. In a Minnesotacentric note, it was … Continue reading
Posted in Combinatorics, Math, What's the news?
Tagged combinatorics, congress, FBI, Math humor, Minnesota, Paul Erdos
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Proof by induction
If you’re solving a combinatorial problem depending on a parameter n and the first few values are 1, 1, 2, 5, 14, your sequence is the Catalan numbers. If the next term of the sequence is 42, that constitutes a … Continue reading
“My brain is open” by Bruce Schechter
My Brain Is Open is one of two biographies of Paul Erdős that I know of, the other being Hoffman’s The Man Who Loved Only Numbers. I mostly enjoyed this one; it conveyed a good sense of the subject’s eccentricities … Continue reading
Ken Appel has died
The Times has a very nice obituary of Kenneth Appel, the main mastermind behind the proof of the fourcolor theorem, one of the crowning achievements of graph theory. He also sounds likfair pleasant, interesting man. The advent of computers has … Continue reading
Posted in Combinatorics, What's the news?
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Generating series
Last Wednesday morning lecture, to calculus students, in two sentences: A series that looks like is called a Taylor series. We are very interested in understanding these series and the functions they represent, so it is of the utmost importance … Continue reading
Coloring Sonobe origami, part 2: symmetric coloring
This is a followup to Coloring Sonobe origami, part 1: proper coloring. Symmetric Coloring The most natural first polyhedra to make from the Sonobe unit are, like the octahedron, regular solids. As a result, they have lots of symmetries. Thus, … Continue reading
Posted in Combinatorics, Math, Origami
Tagged Graph theory, group theory, modular origami
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