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Abstracts for the Combinatorics Seminar

Emil Vaughan (Queen Mary University of London) Flag algebras and extremal 3-graph theory

Abstract:
The flag algebra calculus of Razborov provides a formal system for expressing extremal problems in graph and hypergraph theory. One aspect of the theory is that it allows us to obtain solutions to problems by using a computer to do semi-definite programming. This technique has recently proved quite successful in the context of extremal 3-graph theory, where a number of interesting results have been found, and potential new avenues of attack have opened up for some long-standing open problems.

I will give an account of the method, followed by a survey of recent results, which will include a number of conjectures and open problems