Tag Archives: Turan’s problem

The Combinatorics of Cocycles and Borsuk’s Problem.

Posted on June 15, 2011 by

Cocycles Definition:  A -cocycle is a collection of -subsets such that every -set contains an even number of sets in the collection. Alternative definition: Start with a collection of -sets and consider all -sets that contain an odd number of members … Continue reading →

Posted in Combinatorics, Convexity, Open problems | Tagged , , , , | 2 Comments

A Small Debt Regarding Turan’s Problem

Posted on June 9, 2008 by

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 →

Posted in Combinatorics | Tagged , | 2 Comments

Local Events, Turan’s Problem and Limits of Graphs and Hypergraphs

Posted on May 20, 2008 by

I will write a little about how hectic things are now here at HU, and make two (somewhat related) follow-ups on previous posts: Tell you about Turan’s problem, and about Balázs Szegedi’s lecture from Marburg dealing with limits of graphs and hypergraphs.  Local Events … Continue reading →

Posted in Combinatorics, Open problems | Tagged , , , | 3 Comments

Extremal Combinatorics I: Extremal Problems on Set Systems

Posted on May 1, 2008 by

The “basic notion seminar” is an initiative of David Kazhdan who joined HU math department  around 2000. People give series of lectures about basic mathematics (or not so basic at times). Usually, speakers do not talk about their own research and not even … Continue reading →

Posted in Open problems | Tagged , , , , , | 11 Comments