On the Homotopy Theory of Stratified Spaces

This thesis is broken into two parts. In the first part (Chapters 2 to 6) is dedicated to proving a 'homtopy hypothesis' for stratified spaces. Specifically, given a poset P, we show that the ∞-category Strₚ of ∞-categories with a conservative functor to P can be obtained from the ordinary...

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Bibliographic Details
Main Author: Haine, Peter J.
Other Authors: Barwick, Clark
Format: Thesis
Published: Massachusetts Institute of Technology 2022
Online Access:https://hdl.handle.net/1721.1/139376
https://orcid.org/0000-0002-6662-2035
Description
Summary:This thesis is broken into two parts. In the first part (Chapters 2 to 6) is dedicated to proving a 'homtopy hypothesis' for stratified spaces. Specifically, given a poset P, we show that the ∞-category Strₚ of ∞-categories with a conservative functor to P can be obtained from the ordinary category of P-stratified topological spaces by inverting a class of weak equivalences. For suitably nice P-stratified topological spaces, the corresponding object of Strₚ is the exit-path ∞-category of MacPherson, Treumann, and Lurie. To prove this stratified homotopy hypothesis, we define combinatorial simplicial model structure on the category of simplicial sets over the nerve of 𝑃 whose underlying ∞-category is the ∞-category Strₚ. This model structure on P-stratified simplicial sets allows us to easily compare other theories of P-stratified spaces to ours and deduce that they all embed into ours. The second part (Chapters 7 to 9) explores a number of consequences of this stratified homotopy hypothesis, as well as related results on exit-path ∞-categories and constructible sheaves. This includes an overview of our joint work with Bariwck and Glasman on exit-path categories in algebraic geometry; this work uses as input the perspective on stratified spaces provided by our stratified homotopy hypothesis.