Equivariant Nerve Lemma, simplicial difference, and models for configuration spaces on simplicial complexes
Abstract
Wiltshire-Gordon has introduced a homotopy model for ordered configuration spaces on a given simplicial complex. That author asserts that, after a suitable subdivision, his model also works for unordered configuration spaces. We supply details justifying Wiltshire-Gordon's assertion and, more importantly, uncover the equivariant properties of his more-general simplicial-difference model for the complement of a subcomplex inside a larger complex. This is achieved by proving an equivariant version of the Nerve Lemma. In addition, in the case of configuration spaces, we show that a slight variation of the model has better properties: it is regular and sits inside the configuration space as a strong and equivariant deformation retract. Our variant for the configuration-space model comes from a comparison, in the equivariant setting, between Wiltshire's simplicial difference and a well known model for the complement of a full subcomplex on a simplicial complex.
Cite
@article{arxiv.2004.09020,
title = {Equivariant Nerve Lemma, simplicial difference, and models for configuration spaces on simplicial complexes},
author = {Emilio J. González and Jesús González},
journal= {arXiv preprint arXiv:2004.09020},
year = {2020}
}
Comments
Version 2 of this manuscript extends the result in version 1 by developing the equivariant properties of the simplicial difference. A needed equivariant version of the Nerve Lemma is proved. 19 pages