Persistent homological Quillen-McCord theorem

Abstract

The Quillen-McCord theorem (aka Quillen fiber lemma) gives a sufficient condition on a map between classifying spaces of posetal categories to be a homotopy equivalence. Jonathan Ariel Barmak in his paper [arXiv:1005.0538] gives an elementary topological proof and proves a homological version of the theorem. Following his scheme of the proof, we formulate and prove the homological Quillen-McCord theorem, stable with respect to interleaving distances. To formulate the theorem and apply the scheme, we introduce persistence objects as objects in appropriate functor categories, describe a-la barcode decompositions of persistence posets, and prove several results, e.g. order extension principle for objects in Fun(I, Pos) and approximate triviality of left derived functors of approximately trivial objects in Fun(I, R-Mod).