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 Polymath 10 post 6: The ErdosRado sunflower conjecture, and the Turan (4,3) problem: homological approaches.
 Polymath 10 Emergency Post 5: The ErdosSzemeredi Sunflower Conjecture is Now Proven.
 Mind Boggling: Following the work of Croot, Lev, and Pach, Jordan Ellenberg settled the cap set problem!
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 Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
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 A Breakthrough by Maryna Viazovska Leading to the Long Awaited Solutions for the Densest Packing Problem in Dimensions 8 and 24
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 Polymath 10 Emergency Post 5: The ErdosSzemeredi Sunflower Conjecture is Now Proven.
 The KadisonSinger Conjecture has beed Proved by Adam Marcus, Dan Spielman, and Nikhil Srivastava
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 Polymath10post 4: Back to the drawing board?
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Category Archives: Combinatorics
Happy Birthday Richard Stanley!
This week we are celebrating in Cambridge MA , and elsewhere in the world, Richard Stanley’s birthday. For the last forty years, Richard has been one of the very few leading mathematicians in the area of combinatorics, and he found deep, profound, and … Continue reading
Influence, Threshold, and Noise
My dear friend Itai Benjamini told me that he won’t be able to make it to my Tuesday talk on influence, threshold, and noise, and asked if I already have the slides. So it occurred to me that perhaps … Continue reading
Levon Khachatrian’s Memorial Conference in Yerevan
Workshop announcement The National Academy of Sciences of Armenia together American University of Armenia are organizing a memorial workshop on extremal combinatorics, cryptography and coding theory dedicated to the 60th anniversary of the mathematician Levon Khachatrian. Professor Khachatrian started his … Continue reading
Amazing: Peter Keevash Constructed General Steiner Systems and Designs
Here is one of the central and oldest problems in combinatorics: Problem: Can you find a collection S of qsubsets from an nelement set X set so that every rsubset of X is included in precisely λ sets in the collection? … Continue reading
Many triangulated threespheres!
The news Eran Nevo and Stedman Wilson have constructed triangulations with n vertices of the 3dimensional sphere! This settled an old problem which stood open for several decades. Here is a link to their paper How many nvertex triangulations does the 3 … Continue reading
Posted in Combinatorics, Convex polytopes, Geometry, Open problems
Tagged Eran Nevo, Stedman Wilson
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NatiFest is Coming
The conference Poster as designed by Rotem Linial A conference celebrating Nati Linial’s 60th birthday will take place in Jerusalem December 1618. Here is the conference’s webpage. To celebrate the event, I will reblog my very early 2008 post “Nati’s … Continue reading
Posted in Combinatorics, Computer Science and Optimization, Conferences, Updates
Tagged Nati Linial
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Analysis of Boolean Functions – Week 7
Lecture 11 The Cap Set problem We presented Meshulam’s bound for the maximum number of elements in a subset A of not containing a triple x,y,x of distinct elements whose sum is 0. The theorem is analogous to Roth’s theorem … Continue reading
Posted in Combinatorics, Computer Science and Optimization, Teaching
Tagged Cap set problem, Codes, Linearity testing
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Analysis of Boolean Functions week 5 and 6
Lecture 7 First passage percolation 1) Models of percolation. We talked about percolation introduced by Broadbent and Hammersley in 1957. The basic model is a model of random subgraphs of a grid in ndimensional space. (Other graphs were considered later as … Continue reading
Posted in Combinatorics, Computer Science and Optimization, Probability, Teaching
Tagged Arrow's theorem, Percolation
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Analysis of Boolean Functions – week 4
Lecture 6 Last week we discussed two applications of the FourierWalsh plus hypercontractivity method and in this lecture we will discuss one additional application: The lecture was based on a 5pages paper by Ehud Friedgut and Jeff Kahn: On the number … Continue reading
Analysis of Boolean Functions – Week 3
Lecture 4 In the third week we moved directly to the course’s “punchline” – the use of FourierWalsh expansion of Boolean functions and the use of Hypercontractivity. Before that we started with a very nice discrete isoperimetric question on a … Continue reading