Author Archives: Gil Kalai

Thomas Vidick: What it is that we do

Originally posted on MyCQstate:
This post is a follow-up on some somewhat off-hand comments that I made earlier regarding the notion of truth in a “proof-based” discipline such as pure mathematics or theoretical computer science. Since the former is easier…

Posted in What is Mathematics | Tagged | 1 Comment

To cheer you up in difficult times 20: Ben Green presents super-polynomial lower bounds for off-diagonal van der Waerden numbers W(3,k)

What will be the next polymath project? click here for our post about it.  New lower bounds for van der Waerden numbers by Ben Green Abstract: We show that there is a red-blue colouring of [N] with no blue 3-term … Continue reading

Posted in Combinatorics, Number theory | Tagged , | 2 Comments

To cheer you up in difficult times 19: Nati Linial and Adi Shraibman construct larger corner-free sets from better numbers-on-the-forehead protocols

What will be the next polymath project? click here for our previous post.  Number on the forehead, communication complexity, and additive combinatorics Larger Corner-Free Sets from Better NOF Exactly-N Protocols, by Nati Linial and Adi Shraibman Abstract: A subset of … Continue reading

Posted in Combinatorics, Computer Science and Optimization | Tagged , | 3 Comments

Possible future Polymath projects (2009, 2021)

What will be our next polymath project? A polymath project (Wikipedia) is a collaboration among mathematicians to solve important and difficult mathematical problems by coordinating many mathematicians to communicate with each other on finding the best route to the solution. … Continue reading

Posted in Combinatorics, Mathematics over the Internet, Open discussion | Tagged , , | 22 Comments

Peter Cameron: Doing research

Originally posted on Peter Cameron's Blog:
Probably every research mathematician has been asked the question, “How do you do mathematical research?” Some lay people think we simply figure out ways of doing bigger and bigger long multiplications. Many more…

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To cheer you up in difficult times 18: Beautiful drawings by Neta Kalai for my book: “Gina Says”

In 2009 I wrote a book “Gina Says” that appeared here on the blog, about the adventures of “Gina” in the blogsphere. In 2017 the book (edited and shortened a little) appeared in “world scientific.” The most important additions were … Continue reading

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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.

Stavros Argyrios Papadakis, Vasiliki Petrotou, and Karim Adiprasito In 2018, I reported here about Karim Adiprasito’s proof of the g-conjecture for simplicial spheres.  This conjecture by McMullen from 1970 was considered a holy grail of algebraic combinatorics and it resisted … Continue reading

Posted in Algebra, Combinatorics, Geometry | Tagged , , , , | 4 Comments

Igor Pak: What if they are all wrong?

Originally posted on Igor Pak's blog:
Conjectures are a staple of mathematics. They are everywhere, permeating every area, subarea and subsubarea. They are diverse enough to avoid a single general adjective. They come in al shapes and sizes. Some…

Posted in Combinatorics, Computer Science and Optimization, Geometry, What is Mathematics | Tagged | 6 Comments

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!

Dong Yeap Kang, Tom Kelly, Daniela Kühn, Abhishek Methuku, and Deryk Osthus have just uploaded a paper to the arXive, A proof of the Erdős-Faber-Lovász conjecture. (I am thankful to Nati Linial and Ryan Alweiss for telling me about it.) … Continue reading

Posted in Combinatorics, Updates | Tagged , , , , , | 4 Comments

Open problem session of HUJI-COMBSEM: Problem #5, Gil Kalai – the 3ᵈ problem

This post continues to describe problems presented at our open problems session back in November 2020. Here is the first post in the series.  Today’s problem was presented by me, and it was an old 1989 conjecture of mine. A … Continue reading

Posted in Combinatorics, Computer Science and Optimization, Geometry, Open problems | 5 Comments