My Happy Ending Problem

Wednesday, September 10, 2014 - 9:00am - 9:50am
Keller 3-180
János Pach (École Polytechnique Fédérale de Lausanne (EPFL))
A set system is a k-fold covering of space if every point is contained in at least k sets. A 1-fold covering is called simply a covering. In 1980, motivated by a question of Laszlo Fejes Toth, I raised the following question. Given a plane convex set C, does there exist an integer k=k(C) such that every k-fold covering of the plane splits into 2 coverings? The same question makes sense in higher dimension. This problem has turned out to be relevant in sensor network scheduling and has generated a lot of research during the past 3 and a half decades.

In this talk, I will summarize the curious history of the problem, and give a survey of the most important results and related open problems.
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