Orateur: Katharine Turner (EPFL)
Titre: Generalizations of the Rips Filtration for quasi-metric spaces with corresponding stability results.
Résumé: Rips filtrations over a finite metric space and their corresponding persistent homology are prominent methods in Topological Data Analysis to summarize the ``shape'' of data. For finite metric space X and distance r the traditional Rips complex with parameter r is the flag complex whose vertices are the points in X and whose edges are {[x,y]: d(x,y)≤r}. From considering how the homology of these complexes evolves we can create persistence modules (and their associated barcodes and persistence diagrams). Crucial to their use is the stability result that says if X and Y are finite metric space then the bottleneck distance between persistence modules constructed by the Rips filtration is bounded by 2D(X,Y) (where D is the Gromov-Hausdorff distance). Using the asymmetry of the distance function we construct four different constructions analogous to the persistent homology of the Rips filtration and show they also are stable with respect to the Gromov-Hausdorff distance. These different constructions involve ordered-tuple homology, symmetric functions of the distance function, strongly connected components and poset topology.

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