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Related papers: Second mod $2$ homology of Artin groups

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In this paper, we compute the second integral homology of even Artin groups using Hopf's formula. We then apply our results to the computation of cup products and Pontryagin products on even Artin groups, as well as to the second integral…

Group Theory · Mathematics 2025-07-09 Toshiyuki Akita

Given a finitely presented group $G$, Hopf's formula expresses the second integral homology of $G$ in terms of generators and relators. We give an algorithm that exploits Hopf's formula to estimate $H_2(G;k)$, with coefficients in a finite…

Algebraic Topology · Mathematics 2012-11-13 Joshua Roberts

We give formulas for the second and third integral homology of an arbitrary finitely generated Coxeter group, solely in terms of the corresponding Coxeter diagram. The first of these calculations refines a theorem of Howlett, while the…

Algebraic Topology · Mathematics 2020-11-11 Rachael Boyd

Letting $G=F/R$ be a finitely-presented group, Hopf's formula expresses the second integral homology of $G$ in terms of $F$ and $R$. Expanding on previous work, we explain how to find generators of $H_2(G;\mathbb{F}_p)$. The context of the…

K-Theory and Homology · Mathematics 2020-09-10 Joshua Roberts

We calculate the mod-two cohomology of all alternating groups together, with both cup and transfer product structures, which in particular determines the additive structure and ring structure of the cohomology of individual groups. We show…

Algebraic Topology · Mathematics 2020-06-12 Chad Giusti , Dev Sinha

We give an explicit formula for the cohomology of a right angled Artin group with group ring coefficients in terms of the cohomology of its defining flag complex.

Geometric Topology · Mathematics 2007-05-23 Craig Jensen , John Meier

This is an old paper put here for archeological purposes. We derive a general formula expressing the second homology of a Lie algebra of the form L\otimes A with coefficients in the trivial module through homology of $L$, cyclic homology of…

K-Theory and Homology · Mathematics 2010-05-18 Pasha Zusmanovich

The result of this paper is the determination of the cohomology of Artin groups of type A_n, B_n and \tilde{A}_{n} with non-trivial local coefficients. The main result is an explicit computation of the cohomology of the Artin group of type…

Algebraic Topology · Mathematics 2007-05-23 Filippo Callegaro , Davide Moroni , Mario Salvetti

Dual presentations of Coxeter groups have recently led to breakthroughs in our understanding of affine Artin groups. In particular, they led to the proof of the $K(\pi, 1)$ conjecture and to the solution of the word problem. Will the "dual…

Group Theory · Mathematics 2025-12-30 Giovanni Paolini

We compute the mod-2 cohomology of the collection of all symmetric groups as a Hopf ring, where the second product is the transfer product of Strickland and Turner. We first give examples of related Hopf rings from invariant theory and…

Algebraic Topology · Mathematics 2014-02-26 Chad Giusti , Paolo Salvatore , Dev Sinha

In this paper, we compute the second homology groups of the automorphism group of a free group with coefficients in the abelianization of the free group and its dual group except for 2-torsion part, using combinatorial group theory.

Algebraic Topology · Mathematics 2012-05-21 Takao Satoh

We use categorical description of the invariant 2-cohomology group of Hopf algebra to compute such cohomology for two finite dimensional Hopf algebras: the group ring of $Z_8\rtimes Aut(Z_8)$ and Kac-Paljutkin algebra. For the first of…

Quantum Algebra · Mathematics 2025-10-10 Debashish Goswami , Kiran Maity

We compute: * the cohomology with group ring coefficients of Artin groups (or actually, of their associated Salvetti complexes), Bestvina-Brady groups, and graph products of groups, * the L^2-Betti numbers of Bestvina-Brady groups and of…

Group Theory · Mathematics 2014-07-24 Michael W. Davis , Boris Okun

Minahan and the author recently proved results that allow the calculation of the second rational cohomology group of the Torelli group. This builds on two key ingredients: Hain's calculation of the image of the cup product pairing on the…

Geometric Topology · Mathematics 2026-04-28 Andrew Putman

We show that the direct sum of the cohomology groups of the alternating subgroups of the family of Coxeter groups of Type B exhibits an almost-Hopf ring structure. We apply techniques developed by Giusti and Sinha to fully compute a…

Group Theory · Mathematics 2023-12-20 Lorenzo Guerra , Santanil Jana

In this summary paper, we present the key ideas behind the recent proof of the $K(\pi, 1)$ conjecture for affine Artin groups, which states that complements of locally finite affine hyperplane arrangements with real equations and stable…

Group Theory · Mathematics 2025-09-03 Giovanni Paolini , Mario Salvetti

In this paper we compute the mod 2 cohomology of the McLaughlin group, which is one of the sporadic simple groups.

Algebraic Topology · Mathematics 2008-02-03 Alejandro Adem , R. James Milgram

We explicitly compute the homology groups with coefficients in a field of characteristic zero of cocyclic subgroups or even Artin groups of FC-type. We also give some partial results in the case when the coefficients are taken in a field of…

The purpose of this paper is to put together a large amount of results on the $K(\pi,1)$ conjecture for Artin groups, and to make them accessible to non-experts. Firstly, this is a survey, containing basic definitions, the main results,…

Group Theory · Mathematics 2012-12-03 Luis Paris

For Artin groups of dihedral type, we compute the Bredon homology groups of the classifying space for the family of virtually cyclic subgroups with coefficients in the K-theory of a group ring.

Algebraic Topology · Mathematics 2022-05-20 Yago Antolín , Ramón Flores
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