Cubical Approximation for Directed Topology II

TL;DR

This paper extends classical homotopy equivalences to directed topology using cubical sets, enabling combinatorial calculations of directed homotopy invariants and characterizing category isomorphisms via homotopy theory.

Contribution

It establishes an equivalence between directed homotopy categories of cubical sets and topological spaces, extending classical results to directed settings.

Findings

Equivalence between directed homotopy categories of cubical sets and topological spaces.

Calculations of directed homotopy monoids and cohomology monoids.

Characterization of category isomorphisms via directed homotopy equivalences.

Abstract

The paper establishes an equivalence between directed homotopy categories of (diagrams of) cubical sets and (diagrams of) directed topological spaces. This equivalence both lifts and extends an equivalence between classical homotopy categories of cubical sets and topological spaces. Some simple applications include combinatorial descriptions and subsequent calculations of directed homotopy monoids and directed singular 1-cohomology monoids. Another application is a characterization of isomorphisms between small categories up to zig-zags of natural transformations as directed homotopy equivalences between directed classifying spaces. Cubical sets throughout the paper are taken to mean presheaves over the minimal symmetric monoidal variant of the cube category. Along the way, the paper characterizes morphisms in this variant as the interval-preserving lattice homomorphisms between finite Boolean lattices.