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**Topological Data Analysis**## Curvature sets over persistence diagrams

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Facundo Memoli, Ohio State University
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**Wednesday, April 28, 2021**

**Abstract**: We study an invariant of compact metric spaces which combines the notion of curvature sets introduced by Gromov in the 1980s together with the notion of Vietoris-Rips persistent homology. For given integers k≥0 and n≥1 these invariants arise by considering the degree k Vietoris-Rips persistence diagrams of all subsets of a given metric space with cardinality at most n. We call these invariants (n,k)-persistence sets. We argue that computing these invariants could be significantly easier than computing the usual Vietoris-Rips persistence diagrams. We establish stability results for these invariants and we also precisely characterize some of them in the case of spheres with geodesic and Euclidean distances. We also identify a rich family of metric graphs for which the (4,1)-persistence sets fully recover their homotopy type. Along the way we prove some useful properties of Vietoris-Rips persistence diagrams.