The configuration functor of a punctured space
Abstract
Let be a space whose one point compactification is a CW-complex for which the added point is the only -cell. We observe that the configuration space of numbered distinct points in has no closed support homology in degree and prove that Borel-Moore homology group depends only on the fundamental group . We describe this homology group in terms of a presentation of . A case of interest is when is a connected closed oriented surface of positive genus minus a finite nonempty set. Then the mapping class group of acts on both and and we prove that its action on the latter is through its action on the nilpotent quotient . Furthermore, we give an example of a mapping class of a once punctured closed surface which acts trivially on , but not on the nilpotent quotient . The former generalizes a theorem of Bianchi-Miller-Wilson and the latter disproves a conjecture of theirs.
Keywords
Cite
@article{arxiv.2507.14366,
title = {The configuration functor of a punctured space},
author = {Eduard Looijenga and Andreas Stavrou},
journal= {arXiv preprint arXiv:2507.14366},
year = {2025}
}