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A saturated fusion system over a finite $p$-group $S$ is a category whose objects are the subgroups of $S$ and whose morphisms are injective homomorphisms between the subgroups satisfying certain axioms. A fusion system over $S$ is realized…

Group Theory · Mathematics 2023-07-13 Carles Broto , Jesper Møller , Bob Oliver , Albert Ruiz

For a prime number $p$, a finite $p$-group of order $p^n$ has maximal class if it has nilpotency class $n-1$. Here we examine saturated fusion systems on maximal class $p$-groups and, in particular, we describe all the reduFor a prime…

Group Theory · Mathematics 2022-07-22 Valentina Grazian , Christopher Parker

We define here two new classes of saturated fusion systems, reduced fusion systems and tame fusion systems. These are motivated by our attempts to better understand and search for exotic fusion systems: fusion systems which are not the…

Algebraic Topology · Mathematics 2014-02-26 Kasper K. S. Andersen , Bob Oliver , Joana Ventura

We study a saturated fusion system F on a finite 2-group S having a Baumann component based on a dihedral 2-group. Assuming F is 2-perfect with no nontrivial normal 2-subgroups, and the centralizer of the component is a cyclic 2-group, it…

Group Theory · Mathematics 2021-04-15 Justin Lynd

Saturated fusion systems are categories generalizing important aspects of conjugacy of $p$-subgroups in finite groups. It was shown by Chermak that there are group-like structures called regular localities associated to saturated fusion…

Group Theory · Mathematics 2026-04-01 Ellen Henke

A character table $X$ for a saturated fusion system $\mathcal{F}$ on a finite $p$-group $S$ is the square matrix of values associated to a basis of the lattice of virtual $\mathcal{F}$-stable ordinary characters of $S$. We investigate a…

Representation Theory · Mathematics 2026-05-21 Thomas Lawrence , Jason Semeraro

Saturated fusion systems are categories modeling properties of conjugacy of p-subgroups in finite groups. It was shown by Chermak that they correspond nicely to group-like structures called localities. In this paper we start to explore how…

Group Theory · Mathematics 2026-04-01 Ellen Henke , Edoardo Salati

The Benson-Solomon systems comprise a one-parameter family of simple exotic fusion systems at the prime $2$. The results we prove give significant additional evidence that these are the only simple exotic $2$-fusion systems, as conjectured…

Group Theory · Mathematics 2022-04-14 Ellen Henke , Justin Lynd

A p-local finite group consists of a finite p-group S, together with a pair of categories which encode ``conjugacy'' relations among subgroups of S, and which are modelled on the fusion in a Sylow p-subgroup of a finite group. It contains…

Algebraic Topology · Mathematics 2007-05-23 Carles Broto , Natalia Castellana , Jesper Grodal , Ran Levi , Bob Oliver

Let G be group; a finite p-subgroup S of G is a Sylow p-subgroup if every finite p-subgroup of G is conjugate to a subgroup of S. In this paper, we examine the relations between the fusion system over S which is given by conjugation in G…

Group Theory · Mathematics 2011-10-07 Silvia Onofrei

Let $p$ be an odd prime, and let $S$ be a $p$-group with a unique elementary abelian subgroup $A$ of index $p$. We classify the simple fusion systems over all such groups $S$ in which $A$ is essential. The resulting list, which depends on…

Group Theory · Mathematics 2021-02-02 David A. Craven , Bob Oliver , Jason Semeraro

Let $G$ be a finite group and $H$ be a subgroup of $G$. Then $H$ is called a weakly $S\Phi$-supplemented subgroup of $G$, if there exists a subgroup $T$ of $G$ such that $G =HT$ and $H \cap T \leq \Phi (H) H_{sG}$, where $H_{sG}$ denotes…

Group Theory · Mathematics 2024-07-29 Shengmin Zhang , Zhencai Shen

Let $\mathcal{F}$ be a saturated fusion system on a $p$-group $S$. We study the ring $R(\mathcal{F})$ of $\mathcal{F}$-stable characters by exploiting a new connection to the modular characters of a finite group $G$ with $\mathcal{F} =…

Representation Theory · Mathematics 2024-09-13 Thomas Lawrence

We consider the Burnside ring $A(\mathcal{F})$ of $\mathcal{F}$-stable $S$-sets for a saturated fusion system $\mathcal{F}$ defined on a $p$-group $S$. It is shown by S. P. Reeh that the monoid of $\mathcal{F}$-stable sets is a free…

Algebraic Topology · Mathematics 2014-03-31 Matthew Gelvin , Sune Precht Reeh , Ergun Yalcin

We determine for which known finite simple groups $G$ and which primes $p$ the $p$-fusion system of $G$ is simple. This means first collecting together the results that were already known (and correcting two errors made in an earlier study…

Group Theory · Mathematics 2022-11-08 Bob Oliver , Albert Ruiz

The transporter systems of Oliver and Ventura and the localities of Chermak are classes of algebraic structures that model the $p$-local structures of finite groups. Other than the transporter categories and localities of finite groups,…

Group Theory · Mathematics 2023-03-22 Ellen Henke , Assaf Libman , Justin Lynd

We compare four different types of realizability for saturated fusion systems over discrete $p$-toral groups. For example, when $G$ is a locally finite group all of whose $p$-subgroups are artinian (hence discrete $p$-toral), we show that…

Group Theory · Mathematics 2025-05-26 Carles Broto , Ran Levi , Bob Oliver

We show that every (not necessarily saturated) fusion system can be realized as a full subcategory of the fusion system of a finite group. This result extends our previous work \cite{Park2010} and complements the related result…

Representation Theory · Mathematics 2015-08-25 Sejong Park

For a finite group G of Lie type and a prime p, we compare the automorphism groups of the fusion and linking systems of G at p with the automorphism group of G itself. When p is the defining characteristic of G, they are all isomorphic,…

Group Theory · Mathematics 2016-01-19 Carles Broto , Jesper M. Møller , Bob Oliver

This paper addresses fusion of labeled random finite set (LRFS) densities according to the criterion of minimum information loss (MIL). The MIL criterion amounts to minimizing the (weighted) sum of Kullback-Leibler divergences (KLDs) with…

Systems and Control · Electrical Eng. & Systems 2020-12-02 Lin Gao , Giorgio Battistelli , Luigi Chisci