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In this paper we present several algorithms related with the computation of the homology of groups, from a geometric perspective (that is to say, carrying out the calculations by means of simplicial sets and using techniques of Algebraic…

Algebraic Topology · Mathematics 2013-03-06 Ana Romero , Julio Rubio

In this paper, we develop the theory of equivariant motivic homotopy theory, both unstable and stable. While our original interest was in the case of profinite group actions on smooth schemes, we discuss our results in as broad a setting as…

Algebraic Topology · Mathematics 2014-04-08 Gunnar Carlsson , Roy Joshua

If K is a discrete group and Z is a K-spectrum, then the homotopy fixed point spectrum Z^{hK} is Map_*(EK_+, Z)^K, the fixed points of a familiar expression. Similarly, if G is a profinite group and X is a discrete G-spectrum, then X^{hG}…

Algebraic Topology · Mathematics 2013-12-02 Daniel G. Davis

We study the problem of computing the isolated regular solutions of a system \((f_1,\ldots,f_n)\) of \(n\) polynomial equations in \(n\) variables \((X_1, \dots, X_n)\) over a field of characteristic zero \(k\). We focus on systems with a…

Symbolic Computation · Computer Science 2026-05-22 Thi Xuan Vu

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

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

Let $X,Y$ be $(n-1)$-connected finite pointed CW-complexes of dimension at most $n+2$, $n\geq 3$. In this paper we give elementary proofs of the abelian group structure of $[X,Y]$ of homotopy classes of based maps from $X$ to $Y$, which was…

Algebraic Topology · Mathematics 2024-02-02 Pengcheng Li

For $\Cc$ a $G$-category, we give a condition on a diagram of simplicial sets indexed on $\Cc$ that allows us to define a natural $G$-action on its homotopy colimit, and in some other simplicial sets and categories defined in terms of the…

Algebraic Topology · Mathematics 2007-05-23 Rafael Villarroel-Flores

Let $G$ be a finite group acting on a small category $I$. We study functors $X \colon I \to \mathscr{C}$ equipped with families of compatible natural transformations that give a kind of generalized $G$-action on $X$. Such objects are called…

Algebraic Topology · Mathematics 2016-03-09 Emanuele Dotto , Kristian Moi

In this paper, we review a method for computing and parameterizing the set of homotopy classes of chain maps between two chain complexes. This is then applied to finding topologically meaningful maps between simplicial complexes, which in…

Computational Geometry · Computer Science 2011-08-18 Andrew Tausz , Gunnar Carlsson

We build model structures on the category of equivariant simplicial operads with weak equivalences determined by families of subgroups, in the context of operads with a varying set of colors (and building on the fixed color model structures…

Algebraic Topology · Mathematics 2022-12-21 Peter Bonventre , Luis Alexandre Pereira

We develop an elementary method to compute spaces of equivariant maps from a homogeneous space $G/H$ of a Lie group $G$ to a module of this group. The Lie group is not required to be compact. More generally, we study spaces of invariant…

Representation Theory · Mathematics 2024-04-16 Vincent Knibbeler

We study methods for finding the solution set of a generic system in a family of polynomial systems with parametric coefficients. We present a framework for describing monodromy based solvers in terms of decorated graphs. Under the…

Algebraic Geometry · Mathematics 2018-04-18 Timothy Duff , Cvetelina Hill , Anders Jensen , Kisun Lee , Anton Leykin , Jeff Sommars

A spectral sequence calculating the homology groups of some spaces of maps equivariant under compact group actions is described. For the main example, we calculate the rational homology groups of spaces of even and odd maps $S^m \to S^M$,…

Algebraic Topology · Mathematics 2021-07-01 Victor Vassiliev

In the present paper we show a dichotomy theorem for the complexity of polynomial evaluation. We associate to each graph H a polynomial that encodes all graphs of a fixed size homomorphic to H. We show that this family is computable by…

Computational Complexity · Computer Science 2012-10-30 Nicolas de Rugy-Altherre

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 work we obtain the general form of polynomial mappings that commute with a linear action of a relative symmetry group. The aim is to give results for relative equivariant polynomials that correspond to the results for relative…

Dynamical Systems · Mathematics 2014-11-25 Patricia Hernandes Baptistelli , Miriam Manoel

In this paper, for a finite group, we discuss a method for calculating equivariant homology with constant coefficients. We apply it to completely calculate the geometric fixed points of the equivariant spectrum representing equivariant…

Algebraic Topology · Mathematics 2020-11-24 Sophie Kriz

We develop a new method in the computation of equivariant homotopy, which is based on the splitting of cofiber sequences associated to universal spaces in the category of equivariant spectra. In particular, we use this method to compute the…

Algebraic Topology · Mathematics 2023-03-13 Yutao Liu

Developing an algorithm for computing the Betti numbers of semi-algebraic sets with singly exponential complexity has been a holy grail in algorithmic semi-algebraic geometry and only partial results are known. In this paper we consider the…

Algebraic Topology · Mathematics 2022-07-22 Saugata Basu , Negin Karisani