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Morphisms are homomorphisms under the concatenation operation of the set of words over a finite set. Changing the elements of the finite set does not essentially change the morphism. We propose a way to select a unique representing member…

Combinatorics · Mathematics 2016-01-14 F. Michel Dekking

Motivated by applications in Topological Data Analysis, we consider decompositions of a simplicial complex induced by a cover of its vertices. We study how the homotopy type of such decompositions approximates the homotopy of the simplicial…

Algebraic Topology · Mathematics 2020-02-11 Wojciech Chacholski , Alvin Jin , Martina Scolamiero , Francesca Tombari

We describe the relation of $r$-similarity and finite-order invariants on the homotopy set $[S^1,Y]=\pi_1(Y)$.

Algebraic Topology · Mathematics 2026-02-16 S. S. Podkorytov

In the branch of mathematics known as graph theory, graphs are considered as a set of points, called vertices, with connections between these points, called edges. The purpose of this paper is to study mappings between two graphs that have…

Combinatorics · Mathematics 2019-03-19 Jeffrey Beyerl , Cameron Sharpe

We study two simplicial complexes arising from a directed graph $G = (V, E)$ with two chosen vertices $s$ and $t$: the *path-free complex*, consisting of all subsets $F \subseteq E$ that contain no path from $s$ to $t$, and the…

Combinatorics · Mathematics 2025-06-12 Darij Grinberg , Lukas Katthän , Joel Brewster Lewis

We consider simplicial complexes that are generated from the binomial random 3-uniform hypergraph by taking the downward-closure. We determine when this simplicial complex is homologically connected, meaning that its zero-th and first…

Combinatorics · Mathematics 2016-04-05 Oliver Cooley , Penny Haxell , Mihyun Kang , Philipp Sprüssel

We consider the problem of finding a homomorphism from an input digraph $G$ to a fixed digraph $H$. We show that if $H$ admits a weak-near-unanimity polymorphism $\phi$ then deciding whether $G$ admits a homomorphism to $H$ (HOM($H$)) is…

Computational Complexity · Computer Science 2020-08-11 Tomás Feder , Jeff Kinne , Ashwin Murali , Arash Rafiey

We construct embeddings G of the category of graphs into categories of R-modules over a commutative ring R which are almost full in the sense that the maps induced by the functoriality of G R[Hom_Graphs(X,Y)] --> Hom_R(GX,GY) are…

Rings and Algebras · Mathematics 2013-05-16 Rüdiger Göbel , Adam J. Przeździecki

Let p be a singular point of a variety. Consider a resolution where the preimage of p is a simple normal crossing divisor E. The combinatorial structure of E is described by a cell complex D(E), called the dual graph or dual complex of E.…

Algebraic Geometry · Mathematics 2012-03-14 János Kollár

A classical result of A. Connes asserts that the Frechet algebra of smooth functions on a smooth compact manifold X provides, by a purely algebraic procedure, the de Rham cohomology of X. Namely the procedure uses Hochschild and cyclic…

alg-geom · Mathematics 2008-02-03 Jean-Paul Brasselet , André Legrand

Let $V$ be a finite set. Let $\mathcal{K}$ be a simplicial complex with its vertices in $V$. In this paper, we discuss some differential calculus on $V$. We construct some constrained homology groups of $\mathcal{K}$ by using the…

Algebraic Topology · Mathematics 2025-05-14 Shiquan Ren

The matching complex of a simple graph $G$ is a simplicial complex consisting of the matchings on $G$. Jeli\'c Milutinovi\'c et al. studied the matching complexes of the polygonal line tilings, and they gave a lower bound for the…

Combinatorics · Mathematics 2022-06-17 Takahiro Matsushita

A detailed proof is given of a theorem describing the centraliser of a transitive permutation group, with applications to automorphism groups of objects in various categories of maps, hypermaps, dessins, polytopes and covering spaces, where…

Group Theory · Mathematics 2018-05-25 Gareth A. Jones

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

Let $G$ be a finite group, let $\pi(G)$ be the set of prime divisors of $|G|$ and let $\Gamma(G)$ be the prime graph of $G$. This graph has vertex set $\pi(G)$, and two vertices $r$ and $s$ are adjacent if and only if $G$ contains an…

Group Theory · Mathematics 2019-02-20 Timothy C. Burness , Elisa Covato

We introduce Hochschild (co-)homology of morphisms of schemes or analytic spaces and study its fundamental properties. In analogy with the cotangent complex we introduce the so called (derived) Hochschild complex of a morphism; the…

Algebraic Geometry · Mathematics 2007-05-23 R. -O. Buchweitz , H. Flenner

A graph $H$ is said to be common if the number of monochromatic labelled copies of $H$ in a red/blue edge colouring of a large complete graph is asymptotically minimized by a random colouring with an equal proportion of each colour. We…

Combinatorics · Mathematics 2025-09-16 Natalie Behague , Natasha Morrison , Jonathan A. Noel

For any given graph $H$, one may define a natural corresponding functional $\|.\|_H$ for real-valued functions by using homomorphism density. One may also extend this to complex-valued functions, once $H$ is paired with a $2$-edge-colouring…

Combinatorics · Mathematics 2022-09-07 Joonkyung Lee , Alexander Sidorenko

Symmetric edge polytopes are a recent and well-studied family of centrally symmetric polytopes arising from graphs. In this paper, we introduce a generalization of this family to arbitrary simplicial complexes. We show how topological…

Combinatorics · Mathematics 2026-02-20 Torben Donzelmann , Thiago Holleben , Martina Juhnke

Given two finite abstract simplicial complexes A and B, one can define a new simplicial complex on the set of simplicial maps from A to B. After adding two technicalities, we call this complex Homsc(A, B). We prove the following dichotomy:…

General Topology · Mathematics 2024-08-16 Sebastian Meyer