# Persistent homology

## From Wikipedia, the free encyclopedia

**Persistent homology** is a method for computing topological features of a space at different spatial resolutions. More persistent features are detected over a wide range of spatial scales and are deemed more likely to represent true features of the underlying space rather than artifacts of sampling, noise, or particular choice of parameters.[1]

*See homology for an introduction to the notation.*

To find the persistent homology of a space, the space must first be represented as a simplicial complex. A distance function on the underlying space corresponds to a filtration of the simplicial complex, that is a nested sequence of increasing subsets. One common method of doing this is via taking the sublevel filtration of the distance to a point cloud, or equivalently, the offset filtration on the point cloud and taking its nerve in order to get the simplicial filtration known as Čech filtration.[2] A similar construction uses a nested sequence of Vietoris-Rips complexes known as the Vietoris-Rips filtration.[3]

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