- Alef Corner: Math Collaboration
- Alef’s Corner: Math Collaboration 2
- To cheer you up in difficult times 11: Immortal Songs by Sabine Hossenfelder and by Tom Lehrer
- To cheer you up in difficult times 10: Noam Elkies’ Piano Improvisations and more
- Quantum Matters
- To cheer you up in difficult times 9: Alexey Pokrovskiy proved that Rota’s Basis Conjecture holds asymptotically
- To Cheer you up in Difficult Times 8: Nathan Keller and Ohad Klein Proved Tomaszewski’s Conjecture on Randomly Signed Sums
- Noam Lifshitz: A new hypercontractivity inequality — The proof!
- To cheer you up in difficult times 7: Bloom and Sisask just broke the logarithm barrier for Roth’s theorem!
Top Posts & Pages
- TYI 30: Expected number of Dice throws
- Quantum Matters
- Gil's Collegial Quantum Supremacy Skepticism FAQ
- To Cheer you up in Difficult Times 8: Nathan Keller and Ohad Klein Proved Tomaszewski's Conjecture on Randomly Signed Sums
- Answer: Lord Kelvin, The Age of the Earth, and the Age of the Sun
- A sensation in the morning news - Yaroslav Shitov: Counterexamples to Hedetniemi's conjecture.
- Elchanan Mossel's Amazing Dice Paradox (your answers to TYI 30)
- Extremal Combinatorics IV: Shifting
- Are Natural Mathematical Problems Bad Problems?
Tag Archives: Topological combinatorics
We launched polymath10 a week ago and it is time for the second post. In this post I will remind the readers what the Erdos-Rado Conjecture and the Erdos-Rado theorem are, briefly mention some points made in the previous post and in … Continue reading
This is a new polymath3 research thread. Our aim is to tackle the polynomial Hirsch conjecture which asserts that there is a polynomial upper bound for the diameter of graphs of -dimensional polytopes with facets. Our research so far was … Continue reading
We had a series of posts (1,2,3,4) “from Helly to Cayley” on weighted enumeration of Q-acyclic simplicial complexes. The simplest case beyond Cayley’s theorem were Q-acyclic complexes with vertices, edges, and triangles. One example is the six-vertex triangulation of the … Continue reading
In the first part of this post we discussed an appealing conjecture regaring an extension of Cayley’s counting trees formula. The number of d-dimensional “hypertrees” should somehow add up to . But it was not clear to us which complexes we want … Continue reading
1. Helly’s theorem and Cayley’s formula Helly’s theorem asserts: For a family of n convex sets in , n > d, if every d+1 sets in the family have a point in common then all members in the family have a point in common. … Continue reading
Turan’s problem asks for the minimum number of triangles on n vertices so that every 4 vertices span a triangle. (Or equivalently, for the maximum number of triangles on n vertices without a “tetrahedron”, namely without having four triangles on … Continue reading