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In this paper, we present a constructive and proof-relevant development of graph theory, including the notion of maps, their faces, and maps of graphs embedded in the sphere, in homotopy type theory. This allows us to provide an elementary…

Logic in Computer Science · Computer Science 2024-11-20 Jonathan Prieto-Cubides , Håkon Robbestad Gylterud

For simple graphs $G$ and $H$, the Hom complex $\mathrm{Hom}(G,H)$ is a polyhedral complex whose vertices are the graph homomorphisms $G\to H$ and whose edges connect the pairs of homomorphisms which differ in a single vertex of $G$. Hom…

Combinatorics · Mathematics 2025-09-08 Soichiro Fujii , Yuni Iwamasa , Kei Kimura , Yuta Nozaki , Akira Suzuki

In this paper, we will show dichotomy theorems for the computation of polynomials corresponding to evaluation of graph homomorphisms in Valiant's model. We are given a fixed graph $H$ and want to find all graphs, from some graph class,…

Computational Complexity · Computer Science 2014-12-02 Christian Engels

By introducing various topologies on the homotopy groups of a topological space, some researchers make these well known notions in algebraic topology more useful and powerful. In this paper, first we recall and review some known topologies…

Algebraic Topology · Mathematics 2026-02-25 Naghme Shahami , Behrooz Mashayekhy

This paper studies a discrete homotopy theory for graphs introduced by Barcelo et al. We prove two main results. First we show that if $G$ is a graph containing no 3- or 4-cycles, then the $n$th discrete homotopy group $A_n(G)$ is trivial…

Combinatorics · Mathematics 2020-03-06 Bob Lutz

We investigate topological realizations of higher-rank graphs. We show that the fundamental group of a higher-rank graph coincides with the fundamental group of its topological realization. We also show that topological realization of…

Combinatorics · Mathematics 2012-05-15 S. Kaliszewski , Alex Kumjian , John Quigg , Aidan Sims

The homotopy group $\pi_{n-k} ({\bf C}^{n+1}-V)$ where $V$ is a hypersurface with a singular locus of dimension $k$ and good behavior at infinity is described using generic pencils. This is analogous to the van Kampen procedure for finding…

alg-geom · Mathematics 2008-02-03 A. Libgober

We present a homotopy theory for a weak version of modular operads whose compositions and contractions are only defined up to homotopy. This homotopy theory takes the form of a Quillen model structure on the collection of simplicial…

Algebraic Topology · Mathematics 2020-07-03 Philip Hackney , Marcy Robertson , Donald Yau

The independence complex of a graph is a simplicial complex whose faces correspond to the independent sets of $G$. While independence complexes have been studied extensively for many graph classes, including square grid graphs, relatively…

Combinatorics · Mathematics 2025-12-25 Himanshu Chandrakar , Anurag Singh

We introduce the notion of graphical discreteness to group theory. A finitely generated group is graphically discrete if whenever it acts geometrically on a locally finite graph, the automorphism group of the graph is compact-by-discrete.…

Group Theory · Mathematics 2025-11-20 Alex Margolis , Sam Shepherd , Emily Stark , Daniel Woodhouse

Following our previous work, we develop an algorithm to compute a presentation of the fundamental group of certain partial compactifications of the complement of a complex arrangement of lines in the projective plane. It applies, in…

Algebraic Geometry · Mathematics 2021-09-09 Rodolfo Aguilar Aguilar

In this paper, using the topology on the set of shape morphisms between arbitrary topological spaces $X$, $Y$, $Sh(X,Y)$, defined by Cuchillo-Ibanez et al. in 1999, we consider a topology on the shape homotopy groups of arbitrary…

Algebraic Topology · Mathematics 2015-11-26 Tayyebe Nasri , Fatemeh Ghanei , Behrooz Mashayekhy , Hanieh Mirebrahimi

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 the theory of covering spaces for k-graphs, obtaining a…

Operator Algebras · Mathematics 2008-05-23 David Pask , John Quigg , Iain Raeburn

In this article, we define a family of regular bipartite graphs and show that the homotopy type of the independence complexes of this family is the wedge sum of spheres of certain dimensions.

Combinatorics · Mathematics 2017-09-15 Nandini Nilakantan , Samir Shukla

We show how to construct a family of groups with simple commutator subgroups from aperiodic 1-vertex, finitely aligned higher rank graphs (which are, in fact, a class of cancellative monoids). Inverse semigroups form the intermediary…

Rings and Algebras · Mathematics 2020-04-07 Mark V Lawson , Alina Vdovina

Naturally occurring diagrams in algebraic topology are commutative up to homotopy, but not on the nose. It was quickly realized that very little can be done with this information. Homotopy coherent category theory arose out of a desire to…

Category Theory · Mathematics 2023-01-12 Emily Riehl

A graph $G$ covers a graph $H$ if there exists a locally bijective homomorphism from $G$ to $H$. We deal with regular covers in which this locally bijective homomorphism is prescribed by an action of a subgroup of ${\rm Aut}(G)$. Regular…

Combinatorics · Mathematics 2014-05-29 Jiří Fiala , Pavel Klavík , Jan Kratochvíl , Roman Nedela

In this survey, we explore recent literature on finding the cores of higher graphs using geometric and topological means. We study graphs, hypergraphs, and simplicial complexes, all of which are models of higher graphs. We study the notion…

History and Overview · Mathematics 2025-06-30 Inés García-Redondo , Claudia Landi , Sarah Percival , Anda Skeja , Bei Wang , Ling Zhou

We generalize some homotopy calculation techniques such as splittings and matching trees that are introduced for the computations in the case of the independence complexes of graphs to arbitrary simplicial complexes, and exemplify their…

Combinatorics · Mathematics 2015-01-28 Demet Taylan

We study topological spaces with a distinguished set of paths, called directed paths. Since these directed paths are generally not reversible, the directed homotopy classes of directed paths do not assemble into a groupoid, and there is no…

Algebraic Topology · Mathematics 2021-01-29 Peter Bubenik