Fusion Systems in Algebra and Topology

Fusion Systems in Algebra and Topology PDF

Author: Michael Aschbacher

Publisher: Cambridge University Press

Published: 2011-08-25

Total Pages: 329

ISBN-13: 1107601002

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A fusion system over a p-group S is a category whose objects form the set of all subgroups of S, whose morphisms are certain injective group homomorphisms, and which satisfies axioms first formulated by Puig that are modelled on conjugacy relations in finite groups. The definition was originally motivated by representation theory, but fusion systems also have applications to local group theory and to homotopy theory. The connection with homotopy theory arises through classifying spaces which can be associated to fusion systems and which have many of the nice properties of p-completed classifying spaces of finite groups. Beginning with a detailed exposition of the foundational material, the authors then proceed to discuss the role of fusion systems in local finite group theory, homotopy theory and modular representation theory. This book serves as a basic reference and as an introduction to the field, particularly for students and other young mathematicians.

Fusion Systems in Algebra and Topology

Fusion Systems in Algebra and Topology PDF

Author: Michael Aschbacher

Publisher:

Published: 2014-05-14

Total Pages: 330

ISBN-13: 9781139101844

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A fusion system over a p-group S is a category whose objects form the set of all subgroups of S, whose morphisms are certain injective group homomorphisms, and which satisfies axioms first formulated by Puig that are modelled on conjugacy relations in finite groups. The definition was originally motivated by representation theory, but fusion systems also have applications to local group theory and to homotopy theory. The connection with homotopy theory arises through classifying spaces which can be associated to fusion systems and which have many of the nice properties of p-completed classifying spaces of finite groups. Beginning with a detailed exposition of the foundational material, the authors then proceed to discuss the role of fusion systems in local finite group theory, homotopy theory and modular representation theory. The book serves as a basic reference and as an introduction to the field, particularly for students and other young mathematicians.

The Theory of Fusion Systems

The Theory of Fusion Systems PDF

Author: David A. Craven

Publisher: Cambridge University Press

Published: 2011-06-23

Total Pages: 385

ISBN-13: 1107005965

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The first book to deal comprehensively with the theory of fusion systems.

Rank 2 Amalgams and Fusion Systems

Rank 2 Amalgams and Fusion Systems PDF

Author: Martin van Beek

Publisher: Springer

Published: 2024-04-22

Total Pages: 0

ISBN-13: 9783031544606

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This monograph provides a comprehensive treatment of the classification of small fusion systems, that is, fusion systems with few essential subgroups. It demonstrates a broad range of techniques from local group theory and fusion systems, several of which can be applied in more general settings. Addressing research problems that have not been treated in the past, it is the first text to explicitly use the amalgam method in this context. Fusion systems offer an enticing way to unify various p-local methods employed in group theory, representation theory and homotopy theory; but as abstract constructions they are still somewhat mysterious. This book paves the way to a broad and systematic study of these categories by applying the amalgam method, thus modernizing a methodology widely used to understand the local structure of finite groups. With this comes an introduction to several vital techniques in local group theory, a generous survey of the structure and modular representation theory of some important families of finite groups, and a demonstration of the value of combinatorial methods in finite group theory and fusion systems. Primarily aimed at researchers active in fusion systems and group amalgams, the book will also be of interest to anyone working with finite groups and their modular representations, group actions on trees, or classifying spaces. The inclusion of preliminary chapters outlining the theoretical prerequisites make it ideal for a short lecture course or as a reading group text for early career researchers and graduate students.

Quaternion Fusion Packets

Quaternion Fusion Packets PDF

Author: Michael Aschbacher

Publisher: American Mathematical Soc.

Published: 2021-04-01

Total Pages: 444

ISBN-13: 1470456656

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Let p p be a prime and S S a finite p p-group. A p p-fusion system on S S is a category whose objects are the subgroups of S and whose morphisms are certain injective group homomorphisms. Fusion systems are of interest in modular representation theory, algebraic topology, and local finite group theory. The book provides a characterization of the 2-fusion systems of the groups of Lie type and odd characteristic, a result analogous to the Classical Involution Theorem for groups. The theorem is the most difficult step in a two-part program. The first part of the program aims to determine a large subclass of the class of simple 2-fusion systems, while part two seeks to use the result on fusion systems to simplify the proof of the theorem classifying the finite simple groups.

On Fusion Systems of Component Type

On Fusion Systems of Component Type PDF

Author: Michael Aschbacher

Publisher: American Mathematical Soc.

Published: 2019-02-21

Total Pages: 182

ISBN-13: 1470435209

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This memoir begins a program to classify a large subclass of the class of simple saturated 2-fusion systems of component type. Such a classification would be of great interest in its own right, but in addition it should lead to a significant simplification of the proof of the theorem classifying the finite simple groups. Why should such a simplification be possible? Part of the answer lies in the fact that there are advantages to be gained by working with fusion systems rather than groups. In particular one can hope to avoid a proof of the B-Conjecture, a important but difficult result in finite group theory, established only with great effort.

Automorphisms of Fusion Systems of Finite Simple Groups of Lie Type

Automorphisms of Fusion Systems of Finite Simple Groups of Lie Type PDF

Author: Carles Broto

Publisher: American Mathematical Soc.

Published: 2020-02-13

Total Pages: 115

ISBN-13: 1470437724

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For a finite group G of Lie type and a prime p, the authors 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, with a very short list of exceptions. When p is different from the defining characteristic, the situation is much more complex but can always be reduced to a case where the natural map from Out(G) to outer automorphisms of the fusion or linking system is split surjective. This work is motivated in part by questions involving extending the local structure of a group by a group of automorphisms, and in part by wanting to describe self homotopy equivalences of BG∧p in terms of Out(G).

Reduced Fusion Systems over 2-Groups of Sectional Rank at Most 4

Reduced Fusion Systems over 2-Groups of Sectional Rank at Most 4 PDF

Author: Bob Oliver

Publisher: American Mathematical Soc.

Published: 2016-01-25

Total Pages: 100

ISBN-13: 1470415488

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The author classifies all reduced, indecomposable fusion systems over finite -groups of sectional rank at most . The resulting list is very similar to that by Gorenstein and Harada of all simple groups of sectional -rank at most . But this method of proof is very different from theirs, and is based on an analysis of the essential subgroups which can occur in the fusion systems.

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