HUJI Combinatorics Seminar 


When: Monday November 8th, 2021, at 3PM (Israel time)


Where: B400 in the CS\Engineering building



Speaker: Eran Nevo (HUJI)

Title: clique complexes and flag spheres


Abstract:


A (finite) simplicial complex consisting of the complete subgraphs of a graph is called a clique complex, or flag complex, and if its geometric realization is topologically a sphere it is called a flag sphere. 
Question: What are the possible face numbers of clique complexes? Of flag spheres?
Starting with Turan's theorem, I will mention a refinement of it that takes homology into account; an improved Lower Bound Theorem for flag spheres, as well as other recent progress, and open problems, around the question above. 
This path will lead us also to the study of stable sets in flag spheres. 

Based on joint works with Ernest Chong and with Maria Chudnovsky.