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The nerve theorem is a basic result of algebraic topology that plays a central role in computational and applied aspects of the subject. In topological data analysis, one often needs a nerve theorem that is functorial in an appropriate…

Algebraic Topology · Mathematics 2025-06-04 Ulrich Bauer , Michael Kerber , Fabian Roll , Alexander Rolle

In this paper we construct a Universal chain complex, counting zeros of closed 1-forms on a manifold. The Universal complex is a refinement of the well known Novikov complex; it relates the homotopy type of the manifold, after a suitable…

Differential Geometry · Mathematics 2007-05-23 M. Farber

In this paper we show that the cohomology of a connected CW complex is periodic if and only if it is the base space of an orientable spherical fibration with total space that is homotopically finite dimensional. As applications we…

Algebraic Topology · Mathematics 2007-05-23 Alejandro Adem , Jeff H. Smith

Thomason's Homotopy Colimit Theorem has been extended to bicategories and this extension can be adapted, through the delooping principle, to a corresponding theorem for diagrams of monoidal categories. In this version, we show that the…

Category Theory · Mathematics 2011-03-24 A. R. Garzón , R. Pérez

Let $S^n$ be the $n$-sphere with the geodesic metric and of diameter $\pi$. The intrinsic \v{C}ech complex of $S^n$ at scale $r$ is the nerve of all open balls of radius $r$ in $S^n$. In this paper, we show how to control the homotopy…

Algebraic Topology · Mathematics 2026-04-14 Henry Adams , Ekansh Jauhari , Sucharita Mallick

The main result in this paper is that the space of all smooth links in Euclidean 3-space isotopic to the trivial link of n components has the same homotopy type as its finite-dimensional subspace consisting of configurations of n unlinked…

Geometric Topology · Mathematics 2010-01-11 Tara Brendle , Allen Hatcher

A neural code on $ n $ neurons is a collection of subsets of the set $ [n]=\{1,2,\dots,n\} $. Curto et al. \cite{curto2013neural} associated a ring $\mathcal{R}_{\mathcal{C}}$ (neural ring) to a neural code $\mathcal{C}$. A special class of…

Category Theory · Mathematics 2024-03-27 Neha Gupta , Suhith K N

We show a Whitney Approximation Theorem for a continuous map from a manifold to a smooth CW complex. This enables us to show that a topological CW complex is homotopy equivalent to a smooth CW complex in a category of topological spaces. It…

Algebraic Topology · Mathematics 2022-08-12 Norio Iwase

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

We show that the intersection of three subgroups in a free group is related to the computation of the third homotopy group $\pi_3$. This generalizes a result of Gutierrez-Ratcliffe who relate the intersection of two subgroups with the…

Group Theory · Mathematics 2010-09-01 Hans-Joachim Baues , Roman Mikhailov

We present a new topological connection method for the local bilinear computation of Jacobi sets that improves the visual representation while preserving the topological structure and geometric configuration. To this end, the topological…

Computational Geometry · Computer Science 2022-12-22 Daniel Klötzl , Tim Krake , Youjia Zhou , Jonathan Stober , Kathrin Schulte , Ingrid Hotz , Bei Wang , Daniel Weiskopf

The classifying space of a crossed complex generalises the construction of Eilenberg-Mac Lane spaces. We show how the theory of fibrations of crossed complexes allows the analysis of homotopy classes of maps from a free crossed complex to…

Algebraic Topology · Mathematics 2008-06-25 Ronald Brown

Let $A_1$ be any spectrum in a class of finite spectra whose mod $2$ cohomology is isomorphic to a free module of rank one over the subalgebra $\mathcal{A}(1)$ of the Steenrod algebra. Let $E_{C}$ be the second Morava-$E$ theory associated…

Algebraic Topology · Mathematics 2023-03-22 Viet-Cuong Pham

In this paper, we construct a pointed CW complex called the magnitude homotopy type for a given metric space $X$ and a real parameter $\ell \geq 0$. This space is roughly consisting of all paths of length $\ell$ and has the reduced homology…

Algebraic Topology · Mathematics 2023-05-29 Yu Tajima , Masahiko Yoshinaga

Recently there has been growing interest in discrete homotopies and homotopies of graphs beyond treating graphs as 1-dimensional simplicial spaces. One such type of homotopy is $\times$-homotopy. Recent work by Chih-Scull has developed a…

Combinatorics · Mathematics 2025-04-22 Keira Behal , Tien Chih

For an arbitrary simplicial complex K, Davis and Januszkiewicz have defined a family of homotopy equivalent CW-complexes whose integral cohomology rings are isomorphic to the Stanley-Reisner algebra of K. Subsequently, Buchstaber and Panov…

Algebraic Topology · Mathematics 2014-10-01 Dietrich Notbohm , Nigel Ray

In this paper we describe and continue the study begun by the author, Jones, and Segal, of the homotopy theory that underlies Floer theory. In that paper the authors addressed the question of realizing a Floer complex as the celluar chain…

Algebraic Topology · Mathematics 2008-02-21 Ralph L. Cohen

We investigate one-point reduction methods of finite topological spaces. These methods allow one to study homotopy theory of cell complexes by means of elementary moves of their finite models. We also introduce the notion of h-regular…

Algebraic Topology · Mathematics 2014-10-01 Jonathan Ariel Barmak , Elias Gabriel Minian

Early last century witnessed both the complete classification of 2-dimensional manifolds and a proof that classification of 4-dimensional manifolds is undecidable, setting up 3-dimensional manifolds as a central battleground of topology to…

Geometric Topology · Mathematics 2013-02-28 Carl D. Modes , Marcelo O. Magnasco

For a 1-connected CW-complex $X$, let $\mathcal{E}(X)$ denote the group of homotopy classes of self-homotopy equivalences of $X$. The aim of this paper is to prove that, for every $n\in\Bbb N$, there exists a 1-connected rational CW-complex…

Algebraic Topology · Mathematics 2010-10-08 Mahmoud Benkhalifa