The directed Vietoris-Rips complex and homotopy and singular homology groups of finite digraphs

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Main Authors: Milićević, Nikola, Scoville, Nicholas A.
Format: Preprint
Published: 2024
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author Milićević, Nikola
Scoville, Nicholas A.
author_facet Milićević, Nikola
Scoville, Nicholas A.
contents We prove analogues of classical results for higher homotopy groups and singular homology groups of pseudotopological spaces. Pseudotopological spaces are a generalization of (Čech) closure spaces which are in turn a generalization of topological spaces. Pseudotopological spaces also include graphs and directed graphs as full subcategories. Thus they are a bridge that connects classical algebraic topology with the more applied side of topology. More specifically, we show the existence of a long exact sequence for homotopy groups of pairs of pseudotopological spaces and that a weak homotopy equivalence induces isomorphisms for homology groups. Our main result is the construction of weak homotopy equivalences between the geometric realizations of directed Vietoris-Rips complexes and their underlying directed graphs. This implies that singular homology groups of finite directed graphs can be efficiently calculated from finite combinatorial structures, despite their associated chain groups being infinite dimensional. This work is similar to the work of McCord for finite topological spaces but in the context of pseudotopological spaces. Our results also give a novel approach for studying (higher) homotopy groups of discrete mathematical structures such as (directed) graphs or digital images.
format Preprint
id arxiv_https___arxiv_org_abs_2409_01370
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The directed Vietoris-Rips complex and homotopy and singular homology groups of finite digraphs
Milićević, Nikola
Scoville, Nicholas A.
Algebraic Topology
Category Theory
General Topology
55P10 (Primary), 55N10, 54A05, 18F60 (Secondary)
We prove analogues of classical results for higher homotopy groups and singular homology groups of pseudotopological spaces. Pseudotopological spaces are a generalization of (Čech) closure spaces which are in turn a generalization of topological spaces. Pseudotopological spaces also include graphs and directed graphs as full subcategories. Thus they are a bridge that connects classical algebraic topology with the more applied side of topology. More specifically, we show the existence of a long exact sequence for homotopy groups of pairs of pseudotopological spaces and that a weak homotopy equivalence induces isomorphisms for homology groups. Our main result is the construction of weak homotopy equivalences between the geometric realizations of directed Vietoris-Rips complexes and their underlying directed graphs. This implies that singular homology groups of finite directed graphs can be efficiently calculated from finite combinatorial structures, despite their associated chain groups being infinite dimensional. This work is similar to the work of McCord for finite topological spaces but in the context of pseudotopological spaces. Our results also give a novel approach for studying (higher) homotopy groups of discrete mathematical structures such as (directed) graphs or digital images.
title The directed Vietoris-Rips complex and homotopy and singular homology groups of finite digraphs
topic Algebraic Topology
Category Theory
General Topology
55P10 (Primary), 55N10, 54A05, 18F60 (Secondary)
url https://arxiv.org/abs/2409.01370