English

Relation between intersection homology and homotopy groups

Algebraic Topology 2025-08-05 v2

Abstract

As Goresky and MacPherson intersection homology is not the homology of a space, there is no preferred candidate for intersection homotopy groups. Here, they are defined as the homotopy groups of a simplicial set which P. Gajer associates to a couple (X,p)(X,\overline{p}) of a filtered space and a perversity. We first establish some basic properties for the intersection fundamental groups, as a Van Kampen theorem. For general intersection homotopy groups on Siebenmann CS sets, we prove a Hurewicz theorem between them and the Goresky and MacPherson intersection homology. If the CS set and its intrinsic stratification have the same regular part, we establish the topological invariance of the p\overline{p}-intersection homotopy groups. Several examples justify the hypotheses made in the statements. Finally, intersection homotopy groups also coincide with the homotopy groups of the topological space itself, for the top perversity on a connected, normal Thom-Mather space.

Keywords

Cite

@article{arxiv.2211.06096,
  title  = {Relation between intersection homology and homotopy groups},
  author = {David Chataur and Martintxo Saralegi-Aranguren and Daniel Tanré},
  journal= {arXiv preprint arXiv:2211.06096},
  year   = {2025}
}

Comments

Final version

R2 v1 2026-06-28T05:39:43.195Z