### Recent Comments

Giving a talk at Eli… on Academic Degrees and Sex Johan Aspegren on To Cheer You Up in Difficult T… To cheer you up in d… on Another sensation – Anni… Gil Kalai on To Cheer You Up in Difficult T… Gil Kalai on To Cheer You Up in Difficult T… Alexander Barvinok on To Cheer You Up in Difficult T… Kevin on To Cheer You Up in Difficult T… Gil Kalai on To Cheer You Up in Difficult T… Arseniy on To Cheer You Up in Difficult T… Alexander Barvinok on To Cheer You Up in Difficult T… uniform on To Cheer You Up in Difficult T… Arseniy on To Cheer You Up in Difficult T… -
### Recent Posts

- Giving a talk at Eli and Ricky’s geometry seminar. (October 19, 2021)
- To cheer you up in difficult times 32, Annika Heckel’s guest post: How does the Chromatic Number of a Random Graph Vary?
- To Cheer You Up in Difficult Times 31: Federico Ardila’s Four Axioms for Cultivating Diversity
- Dream a Little Dream: Quantum Computer Poetry for the Skeptics (Part I, mainly 2019)
- To Cheer you up in difficult times 30: Irit Dinur, Shai Evra, Ron Livne, Alex Lubotzky, and Shahar Mozes Constructed Locally Testable Codes with Constant Rate, Distance, and Locality
- To cheer you up in difficult times 29: Free will, predictability and quantum computers
- Alef’s corner: Mathematical research
- Let me tell you about three of my recent papers
- Mathematical news to cheer you up

### Top Posts & Pages

- Giving a talk at Eli and Ricky's geometry seminar. (October 19, 2021)
- Academic Degrees and Sex
- The Argument Against Quantum Computers - A Very Short Introduction
- To Cheer You Up in Difficult Times 31: Federico Ardila's Four Axioms for Cultivating Diversity
- To cheer you up in difficult times 32, Annika Heckel's guest post: How does the Chromatic Number of a Random Graph Vary?
- Amazing: Karim Adiprasito proved the g-conjecture for spheres!
- To cheer you up in difficult times 11: Immortal Songs by Sabine Hossenfelder and by Tom Lehrer
- Must-read book by Avi Wigderson
- Richard Stanley: How the Proof of the Upper Bound Theorem (for spheres) was Found

### RSS

# Tag Archives: Lou Billera

## Karim Adiprasito: The g-Conjecture for Vertex Decomposible Spheres

J Scott Provan (site) The following post was kindly contributed by Karim Adiprasito. (Here is the link to Karim’s paper.) Update: See Karim’s comment on the needed ideas for extend the proof to the general case. See also in the … Continue reading

Posted in Combinatorics, Convex polytopes, Geometry, Guest blogger
Tagged g-conjecture, J Scott Provan, Karim Adiprasito, Leonid Gurvits, Lou Billera
9 Comments

## Beyond the g-conjecture – algebraic combinatorics of cellular spaces I

The g-conjecture for spheres is surely the one single conjecture I worked on more than on any other, and also here on the blog we had a sequence of posts about it by Eran Nevo (I,II,III,IV). Here is a great … Continue reading

Posted in Combinatorics, Convex polytopes, Geometry
Tagged Anders Bjorner, Bob MacPherson, Carl Lee, Ed Swartz, Eran Nevo, g-conjecture, Günter Ziegler, Isabella Novik, June Huh, Kalle Karu, Karim Adiprasito, Kazhdan-Lustig polynomials, Lou Billera, Marge Bayer, Peter McMullen, Richard Stanley, Ron Adin, Satoshi Murai, Tom Braden
12 Comments

## (Eran Nevo) The g-Conjecture I

This post is authored by Eran Nevo. (It is the first in a series of five posts.) Peter McMullen The g-conjecture What are the possible face numbers of triangulations of spheres? There is only one zero-dimensional sphere and it consists … Continue reading

Posted in Combinatorics, Convex polytopes, Guest blogger, Open problems
Tagged Carl Lee, Eran Nevo, face rings, g-conjecture, Lou Billera, Peter McMullen, Polytopes, Richard Stanley
13 Comments

## Euler’s Formula, Fibonacci, the Bayer-Billera Theorem, and Fine’s CD-index

Bill Gessley proving Euler’s formula (at UMKC) In the earlier post about Billerafest I mentioned the theorem of Bayer and Billera on flag numbers of polytopes. Let me say a little more about it. 1. Euler Euler’s theorem asserts that for … Continue reading

Posted in Combinatorics, Convex polytopes
Tagged Bayer-Billera's theorem, CD-index, Flag numbers, Jonathan Fine, Lou Billera, Marge Bayer
8 Comments

## Billerafest

I am unable to attend the conference taking place now at Cornell, but I send my warmest greetings to Lou from Jerusalem. The titles and abstracts of the lectures can be found here. Let me tell you about two theorems by Lou. … Continue reading

Posted in Conferences, Convex polytopes
Tagged f-vectors, flag vectors, g-conjecture, Lou Billera
1 Comment