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Tuesday, January 23, 2018

**Abstract:** Given a large point set in the plane, where is its 'center'? Unlike the 1-dimensional case, there is not a single answer. We will discuss some of these answers, with the focus on the result of Pach. He showed that one can always find three large subsets A,B,C and a 'central point' p such that every A-B-C triangle contains p. We will then explain the topological generalization of this and related results, where for example the triangle edges are no longer assumed to be straight. Based on a joint work with Alfredo Hubard.

Tuesday, January 30, 2018

Tuesday, February 6, 2018

Tuesday, February 13, 2018

Tuesday, February 20, 2018

Tuesday, February 27, 2018

Tuesday, March 6, 2018

Tuesday, March 13, 2018