Although Vietoris–Rips complexes are frequently used in topological data analysis to approximate the “shape” of a dataset, their theoretical properties are not fully understood.
In the case of the circle, these complexes exhibit a surprising progression of homotopy types (from to to , etc.) as the scale increases.
However, much less is known about the Vietoris–Rips complexes of higher-dimensional spheres.
I will present work that explores Vietoris–Rips complexes of the -sphere and shows how the appearance of nontrivial homotopy groups of can be controlled by covering properties of and real projective space .
Specifically, if the first nontrivial homotopy group of occurs in dimension , then can be covered by balls of radius , but there is no covering of by balls of radius .
This is joint work with Henry Adams and Žiga Virk.