Tag Archives: Branko Grunbaum

Joshua Hinman proved Bárány’s conjecture on face numbers of polytopes, and Lei Xue proved a lower bound conjecture by Grünbaum.

Posted on April 29, 2022 by Gil Kalai

Joshua Hinman proved Bárány’s conjecture. One of my first posts on this blog was a 2008 post Five Open Problems Regarding Convex Polytopes, now 14 years later, I can tell you about the first problem on the list to get solved. … Continue reading →

Posted in Combinatorics, Convex polytopes | Tagged , , , | 5 Comments

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

Posted on May 30, 2021 by Gil Kalai

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 , | 1 Comment

Ricky and Branko

Posted on October 14, 2018 by Gil Kalai

Two dear friends, and great geometers, Ricky Pollack and Branko Grünbaum  passed away a few weeks ago. Ricky was a close friend that both Mazi my wife and I loved, and we were both fascinated by his wisdom, charm and … Continue reading →

Posted in Combinatorics, Convexity, Geometry, Obituary | Tagged , | 4 Comments

My Copy of Branko Grünbaum’s Convex Polytopes

Posted on April 26, 2018 by Gil Kalai

Branko Grünbaum is my academic grandfather (see this highly entertaining post for a picture representing five academic generations). Gunter Ziegler just wrote a beautiful article in the Notices of the AMS on Branko Grunbaum’s  classic book “Convex Polytopes”, so this … Continue reading →

Posted in Combinatorics, Convex polytopes, People | Tagged , , | 4 Comments

The World of Michael Burt: When Architecture, Mathematics, and Art meet.

Posted on October 1, 2017 by Gil Kalai

  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 , , | 6 Comments

Budapest, Seattle, New Haven

Posted on October 15, 2010 by Gil Kalai

Here we continue the previous post on Summer 2010 events in Reverse chronological order. Happy birthday Srac In the first week of August we celebrated Endre Szemeredi’s birthday. This was a very impressive conference. Panni, Endre’s wife, assisted by her … Continue reading →

Posted in Blogging, Conferences | Tagged , , , | 8 Comments