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- Peter Cameron: Doing research
- To cheer you up in difficult times 18: Beautiful drawings by Neta Kalai for my book: “Gina Says”
- Amazing: Simpler and more general proofs for the g-theorem by Stavros Argyrios Papadakis and Vasiliki Petrotou, and by Karim Adiprasito, Stavros Argyrios Papadakis, and Vasiliki Petrotou.
- Igor Pak: What if they are all wrong?
- To cheer you up in difficult times 17: Amazing! The Erdős-Faber-Lovász conjecture (for large n) was proved by Dong Yeap Kang, Tom Kelly, Daniela Kühn, Abhishek Methuku, and Deryk Osthus!
- Open problem session of HUJI-COMBSEM: Problem #5, Gil Kalai – the 3ᵈ problem
- To cheer you up in difficult times 16: Optimism, two quotes
- The Argument Against Quantum Computers – A Very Short Introduction
- Open problem session of HUJI-COMBSEM: Problem #4, Eitan Bachmat: Weighted Statistics for Permutations
Top Posts & Pages
- Peter Cameron: Doing research
- TYI 30: Expected number of Dice throws
- Amazing: Simpler and more general proofs for the g-theorem by Stavros Argyrios Papadakis and Vasiliki Petrotou, and by Karim Adiprasito, Stavros Argyrios Papadakis, and Vasiliki Petrotou.
- Igor Pak: What if they are all wrong?
- Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
- The Argument Against Quantum Computers - A Very Short Introduction
- Chomskian Linguistics
- Dan Romik on the Riemann zeta function
- To cheer you up in difficult times 18: Beautiful drawings by Neta Kalai for my book: "Gina Says"
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Tag Archives: Micha A. Perles
Open problem session of HUJI-COMBSEM: Problem #2 Chaya Keller: The Krasnoselskii number
Marilyn Breen This is our second post on the open problem session of the HUJI combinatorics seminar. The video of the session is here. Today’s problem was presented by Chaya Keller. The Krasnoselskii number One of the best-known applications … Continue reading
Posted in Combinatorics, Convexity
Tagged Chaya Keller, Marilyn Breen, Mark Krasnoselskii, Micha A. Perles
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Micha Perles’ Geometric Proof of the Erdos-Sos Conjecture for Caterpillars
A geometric graph is a set of points in the plane (vertices) and a set of line segments between certain pairs of points (edges). A geometric graph is simple if the intersection of two edges is empty or a vertex … Continue reading
Touching Simplices and Polytopes: Perles’ argument
Joseph Zaks (1984), picture taken by Ludwig Danzer (OberWolfach photo collection) The story I am going to tell here was told in several places, but it might be new to some readers and I will mention my own angle, … Continue reading
Posted in Combinatorics, Convex polytopes, Geometry, Open problems
Tagged Joseph Zaks, Micha A. Perles
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Proof By Lice!
From camels to lice. (A proof promised here.) Theorem (Hopf and Pannwitz, 1934): Let be a set of points in the plane in general position (no three points on a line) and consider line segments whose endpoints are in . Then … Continue reading