Category Archives: Combinatorics

Mathematical news to cheer you up

1.  Anna Kiesenhofer, a PhD mathematician researching PDEs at Ecole Polytechnique Federale Lausanne (EPFL), won the gold medal in the women’s bicycle road race at the Olympics. Here are two trivia question: a) Which hero of a recent post over … Continue reading

Posted in Combinatorics, Sport, Uncategorized, Updates | 2 Comments

To cheer you up in difficult times 26: Two real-life lectures yesterday at the Technion

After 16 months without lecturing to an audience in my same location, I gave yesterday two lectures at the Technion in front of a live audience (and some additional audience in remote locations). The main lecture was in COMSOC 2021, … Continue reading

Posted in Combinatorics, Convex polytopes, Economics, Games, Rationality | Tagged | Leave a comment

To Cheer You Up in Difficult times 24: Borodin’s colouring conjecture!

An acyclic colouring of a graph is a colouring of its vertices so that the subgraph spanned on union of every two colour classes is acyclic (a forest). Grunbaum conjectured in 1973 that Every planar graph has acyclic colouring with … Continue reading

Posted in Combinatorics | Tagged , | Leave a comment

To cheer you up in difficult times 25: some mathematical news! (Part 2)

Topology Quasi-polynomial algorithms for telling if a knot is trivial Marc Lackenby announced a quasi-polynomial time algorithm to decide whether a given knot is the unknot! This is a big breakthrough. This question is known to be both in NP … Continue reading

Posted in Algebra, Combinatorics, Geometry, Number theory | 2 Comments

Alef Corner: ICM2022

Alef’s new piece for ICM 2022 will surely cheer you up!

Posted in Art, Combinatorics, Geometry, ICM2022 | Tagged , | Leave a comment

To cheer you up in difficult times 22: some mathematical news! (Part 1)

To cheer you up, in these difficult times, here are (in two parts) some mathematical news that I heard in personal communications or on social media. (Maybe I will write later, in more details,  about few of them that are … Continue reading

Posted in Combinatorics, Convex polytopes, Convexity, Geometry | Leave a comment

Cheerful News in Difficult Times: The Abel Prize is Awarded to László Lovász and Avi Wigderson

The Abel Prize was awarded earlier today to László Lovász and Avi Wigderson “for their foundational contributions to theoretical computer science and discrete mathematics, and their leading role in shaping them into central fields of modern mathematics.” Congratulations to Laci … Continue reading

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

Nostalgia corner: John Riordan’s referee report of my first paper

In 1971/1972 academic year, I was an undergraduate student at the Hebrew University of Jerusalem and toward the end of the year I wrote a paper about Abel’s sums. I sent it to John Riordan the author of the books  … Continue reading

Posted in Combinatorics, personal | Tagged , , , | 7 Comments

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