Laboratory of Mathematical Logic at PDMI

Пятница, 16 мая, комната 106. Начало в 16:00.

Докладчик: Peter Zvengrowski (University of Calgary).

Тема: Relations Between the Colouring of Graphs and Homotopy Theory.

Abstract

In 1955 M. Kneser formulated a conjecture in the partition theory of finite sets that was proved in 1978 by Lovasz, with a more direct approach and simplified proof given two weeks later by Barany. Surprisingly, topological ideas were needed in these proofs.

In this talk we shall study the first theorem Lovasz used in his proof, which has the virtue of applying to colouring any graph, and show how a substantially stronger theorem can be obtained using standard ideas from fibre bundle theory. Other recent work in this area, e.g. by Kriz, Matousek, Ziegler, and Greene will be briefly mentioned.