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 Hardness of Approximating Vertex Cover, PolytopeIntegralityGap, the AlswedeKachatrian theorem, and More.
 Jacob Fox, David Conlon, and Benny Sudakov: Vast Improvement of our Knowledge on Unavoidable Patterns in Words
 Subhash Khot, Dor Minzer and Muli Safra proved the 2to2 Games Conjecture
 Interesting Times in Mathematics: Enumeration Without Numbers, Group Theory Without Groups.
 Cody Murray and Ryan Williams’ new ACC breakthrough: Updates from Oded Goldreich’s Choices
 Yael Tauman Kalai’s ICM2018 Paper, My Paper, and Cryptography
 Ilan Karpas: Frankl’s Conjecture for Large Families
 Third third of my ICM 2018 paper – Three Puzzles on Mathematics, Computation and Games. Corrections and comments welcome
 Second third of my ICM 2018 paper – Three Puzzles on Mathematics, Computation and Games. Corrections and comments welcome
Top Posts & Pages
 Hardness of Approximating Vertex Cover, PolytopeIntegralityGap, the AlswedeKachatrian theorem, and More.
 Subhash Khot, Dor Minzer and Muli Safra proved the 2to2 Games Conjecture
 New Isoperimetric Results for Testing Monotonicity
 Jacob Fox, David Conlon, and Benny Sudakov: Vast Improvement of our Knowledge on Unavoidable Patterns in Words
 Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
 Can Category Theory Serve as the Foundation of Mathematics?
 Believing that the Earth is Round When it Matters
 TYI 30: Expected number of Dice throws
 My Book: "Gina Says," Adventures in the Blogosphere String War
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Category Archives: Combinatorics
Eran Nevo: gconjecture part 4, Generalizations and Special Cases
This is the fourth in a series of posts by Eran Nevo on the gconjecture. Eran’s first post was devoted to the combinatorics of the gconjecture and was followed by a further post by me on the origin of the gconjecture. Eran’s second post was about … Continue reading
Posted in Combinatorics, Convex polytopes, Guest blogger, Open problems
Tagged Eran Nevo, gconjecture
2 Comments
The World of Michael Burt: When Architecture, Mathematics, and Art meet.
This remarkable 3D geometric object tiles space! It is related to a theory of “spacial networks” extensively studied by Michael Burt and a few of his students. The network associated to this object is described in the picture below. … Continue reading
Posted in Art, Combinatorics, Geometry
Tagged Architecture, Branko Grunbaum, Michael Burt
4 Comments
Some Mathematical Puzzles that I encountered during my career
Recently, I gave some lectures based on a generalaudience personal tour across four (plus one) mathematical puzzles that I encountered during my career. Here is a paper based on these lectures which is meant for a very wide audience (in … Continue reading
Elchanan Mossel’s Amazing Dice Paradox (your answers to TYI 30)
TYI 30 asked Elchanan Mossel’s Amazing Dice Paradox (that I heard from Yuval Peres yesterday) You throw a die until you get 6. What is the expected number of throws (including the throw giving 6) conditioned on the event that all throws … Continue reading
Posted in Combinatorics, Probability, Test your intuition
Tagged condition probability, Elchanan Mossel
62 Comments
TYI 30: Expected number of Dice throws
Test your intuition: You throw a dice until you get 6. What is the expected number of throws (including the throw giving 6) conditioned on the event that all throws gave even numbers. followup post
Test your intuition 29: Diameter of various random trees
Both trees in general and random trees in particular are wonderful objects. And there is nothing more appropriate to celebrate Russ Lyons great birthday conference “Elegance in Probability” (taking place now in Tel Aviv) than to test your intuition, dear … Continue reading
Posted in Combinatorics, Probability, Test your intuition
Tagged Russ Lyons, Test your intuition
19 Comments
Micha Perles’ Geometric Proof of the ErdosSos 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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Where were we?
I was slow blogging, and catching up won’t be so easy. Of course, this brings me back to the question of what I should blog about. Ideally, I should tell you about mathematical things I heard about. The problem is … Continue reading