A stratified homotopy hypothesis
Abstract
We show that conically smooth stratified spaces embed fully faithfully into -categories. This articulates a stratified generalization of the homotopy hypothesis proposed by Grothendieck. As such, each -category defines a stack on conically smooth stratified spaces, and we identify the descent conditions it satisfies. These include -invariance and descent for open covers and blow-ups, analogous to sheaves for the h-topology in -homotopy theory. In this way, we identify -categories as striation sheaves, which are those sheaves on conically smooth stratified spaces satisfying the indicated descent. We use this identification to construct by hand two remarkable examples of -categories: , an -category classifying constructible bundles; and , the absolute exit-path -category. These constructions are deeply premised on stratified geometry, the key geometric input being a characterization of conically smooth stratified maps between cones and the existence of pullbacks for constructible bundles.
Cite
@article{arxiv.1502.01713,
title = {A stratified homotopy hypothesis},
author = {David Ayala and John Francis and Nick Rozenblyum},
journal= {arXiv preprint arXiv:1502.01713},
year = {2017}
}
Comments
84 pages; numerous corrections made; definition of constructible bundle modified to add a condition on links, ensuring existence of pullbacks (Lemma 6.1.11)