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# Andreas Holmsen, Fractional Helly and topological complexity

## Tuesday, June 16, 2020 @ 4:30 PM - 5:30 PM KST

Room B232,
IBS (기초과학연구원)

The *fractional Helly theorem* is a simple yet remarkable generalization of Helly’s classical theorem on the intersection of convex sets, and it is of considerable interest to extend the fractional Helly theorem beyond the setting of convexity. In this talk I will discuss a recent result which shows that the fractional Helly theorem holds for families of subsets of $\mathbb R^d$ which satisfy only very weak topological assumptions. The proofs combine a number of tools such as homological minors, stair-convexity, supersaturation in hypergraphs, Radon dimension, and Ramsey-type arguments. This is joint work with Xavier Goaoc and Zuzana Patáková.