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Inspired by work of Fr\"oberg (1990), and Eagon and Reiner (1998), we define the \emph{total $k$-cut complex} of a graph $G$ to be the simplicial complex whose facets are the complements of independent sets of size $k$ in $G$. We study the…

The Hom complex $\mathrm{Hom}(G, H)$ of graphs is a simplicial complex associated to a pair of graphs $G$ and $H$, and its homotopy type is of interest in the graph coloring problem and the homomorphism reconfiguration problem. In this…

Combinatorics · Mathematics 2026-02-04 Takahiro Matsushita

We prove analogues of classical results for higher homotopy groups and singular homology groups of pseudotopological spaces. Pseudotopological spaces are a generalization of (\v{C}ech) closure spaces which are in turn a generalization of…

Algebraic Topology · Mathematics 2024-09-30 Nikola Milićević , Nicholas A. Scoville

For $r\geq 1$, the $r$-independence complex of a graph $G$ is a simplicial complex whose faces are subset $I \subseteq V(G)$ such that each component of the induced subgraph $G[I]$ has at most $r$ vertices. In this article, we determine the…

Algebraic Topology · Mathematics 2021-02-02 Priyavrat Deshpande , Anurag Singh

In this work we use Hodge theoretic methods to study homotopy types of complex projective manifolds with arbitrary fundamental groups. The main tool we use is the \textit{schematization functor} $X \mapsto (X\otimes \mathbb{C})^{sch}$,…

Algebraic Geometry · Mathematics 2014-01-14 L. Katzarkov , T. Pantev , B. Toen

The paper contains an application of van Kampen theorem for groupoids for computation of homotopy types of certain class of non-compact foliated surfaces obtained by gluing at most countably many strips $\mathbb{R}\times(0,1)$ with boundary…

Algebraic Topology · Mathematics 2021-12-07 Sergiy Maksymenko , Oleksii Nikitchenko

The purpose of this paper is to generalise Sullivan's rational homotopy theory to non-nilpotent spaces, providing an alternative approach to defining Toen's schematic homotopy types over any field k of characteristic zero. New features…

Algebraic Topology · Mathematics 2009-02-04 J. P. Pridham

k-graphs are higher-rank analogues of directed graphs which were first developed to provide combinatorial models for operator algebras of Cuntz-Krieger type. Here we develop a theory of the fundamental groupoid of a k-graph, and relate it…

Combinatorics · Mathematics 2007-05-23 David Pask , John Quigg , Iain Raeburn

This paper makes some preliminary observations towards an extension of current work on graphs defined on groups to simplicial complexes. I define a variety of simplicial complexes on a group which are preserved by automorphisms of the…

Combinatorics · Mathematics 2024-11-04 Peter J. Cameron

We introduce homotopy groups of digraphs that admit an intuitive description of grid structures, which is a variation of the GLMY homotopy groups introduced by Grigor'yan, Lin, Muranov and Yau in 2014. This direct approach enables a…

Algebraic Topology · Mathematics 2025-05-06 Jingyan Li , Jie Wu , Shing-Tung Yau , Mengmeng Zhang

We present a mathematical framework for describing the topology of configuration spaces for particles on one-connected graphs. In particular, we compute the homology groups over integers for different classes of one-connected graphs. Our…

Mathematical Physics · Physics 2017-05-24 Tomasz Maciążek , Adam Sawicki

Given finite simple graphs $G$ and $H$, the Hom complex $\mathrm{Hom}(G,H)$ is a polyhedral complex having the graph homomorphisms $G\to H$ as the vertices. We determine the homotopy type of each connected component of $\mathrm{Hom}(G,H)$…

Combinatorics · Mathematics 2025-09-16 Soichiro Fujii , Kei Kimura , Yuta Nozaki

In this note we study a family of graphs of groups over arbitrary base graphs where all vertex groups are isomorphic to a fixed countable sofic group $G$, and all edge groups $H<G$ are such that the embeddings of $H$ into $G$ are identical…

Group Theory · Mathematics 2024-08-22 David Gao , Srivatsav Kunnawalkam Elayavalli , Mahan Mj

We highlight that integer Heisenberg groups at level 2 underlie topological quantum phenomena: their group algebras coincide with the algebras of quantum observables of abelian anyons in fractional quantum Hall (FQH) systems on closed…

Strongly Correlated Electrons · Physics 2026-01-07 Sadok Kallel , Hisham Sati , Urs Schreiber

In this study we introduce the notions of semi-homotopy of semi-continuous maps and of semi-paths. We also construct a group structure, which will be called semi-fundamental group, using semi-loops and explore some properties of…

Algebraic Topology · Mathematics 2016-04-27 Ayhan Erciyes , Ali Aytekin , Tunçar Şahan

We show that diagram groups can be viewed as fundamental groups of spaces of positive paths on directed 2-complexes (these spaces of paths turn out to be classifying spaces). Thus diagram groups are analogs of second homotopy groups,…

Group Theory · Mathematics 2007-05-23 V. S. Guba , M. V. Sapir

We present a new algorithm for computing the first discrete homology group of a graph. By testing the algorithm on different data sets of random graphs, we find that it significantly outperforms other known algorithms.

Computational Geometry · Computer Science 2025-12-17 Jacob Ender , Chris Kapulkin

Coarse geometry, and in particular coarse homotopy theory, has proven to be a powerful tool for approaching problems in geometric group theory and higher index theory. In this paper, we continue to develop theory in this area by proving a…

Geometric Topology · Mathematics 2025-03-03 Thomas Weighill

Motivated by constructions in topological data analysis and algebraic combinatorics, we study homotopy theory on the category of Cech closure spaces $\mathbf{Cl}$, the category whose objects are sets endowed with a Cech closure operator and…

Algebraic Topology · Mathematics 2022-09-28 Antonio Rieser

The homotopy theory of gauge groups has received considerable attention in recent decades. In this work, we study the homotopy theory of gauge groups over some high dimensional manifolds. To be more specific, we study gauge groups of…

Algebraic Topology · Mathematics 2021-03-24 Ruizhi Huang