Subcentric linking systems
HTML articles powered by AMS MathViewer
- by Ellen Henke PDF
- Trans. Amer. Math. Soc. 371 (2019), 3325-3373 Request permission
Abstract:
Linking systems are crucial for studying the homotopy theory of fusion systems, but are also of interest from an algebraic point of view. We propose a definition of a linking system associated to a saturated fusion system which is more general than the one currently in the literature and thus allows a more flexible choice of objects of linking systems. More precisely, we define subcentric subgroups of fusion systems in a way that every quasicentric subgroup of a saturated fusion system is subcentric. Whereas the objects of linking systems in the current definition are always quasicentric, the objects of our linking systems only need to be subcentric. We prove that, associated to each saturated fusion system $\mathcal {F}$, there is a unique linking system whose objects are the subcentric subgroups of $\mathcal {F}$. Furthermore, the nerve of such a subcentric linking system is homotopy equivalent to the nerve of the centric linking system associated to $\mathcal {F}$. We believe that the existence of subcentric linking systems opens a new way for a classification of fusion systems of characteristic $p$-type. The various results we prove about subcentric subgroups give furthermore some evidence that the concept is of interest for studying extensions of linking systems and fusion systems.References
- Kasper K. S. Andersen, Bob Oliver, and Joana Ventura, Reduced, tame and exotic fusion systems, Proc. Lond. Math. Soc. (3) 105 (2012), no. 1, 87–152. MR 2948790, DOI 10.1112/plms/pdr065
- Michael Aschbacher, Generation of fusion systems of characteristic 2-type, Invent. Math. 180 (2010), no. 2, 225–299. MR 2609243, DOI 10.1007/s00222-009-0229-z
- Michael Aschbacher, The generalized Fitting subsystem of a fusion system, Mem. Amer. Math. Soc. 209 (2011), no. 986, vi+110. MR 2752788, DOI 10.1090/S0065-9266-2010-00621-5
- Michael Aschbacher, Fusion systems of $\mathbf {F}_2$-type, J. Algebra 378 (2013), 217–262. MR 3017023, DOI 10.1016/j.jalgebra.2012.12.018
- Michael Aschbacher, $S_3$-free 2-fusion systems, Proc. Edinb. Math. Soc. (2) 56 (2013), no. 1, 27–48. MR 3021403, DOI 10.1017/S0013091512000235
- Michael Aschbacher, Radha Kessar, and Bob Oliver, Fusion systems in algebra and topology, London Mathematical Society Lecture Note Series, vol. 391, Cambridge University Press, Cambridge, 2011. MR 2848834, DOI 10.1017/CBO9781139003841
- Carles Broto, Natàlia Castellana, Jesper Grodal, Ran Levi, and Bob Oliver, Subgroup families controlling $p$-local finite groups, Proc. London Math. Soc. (3) 91 (2005), no. 2, 325–354. MR 2167090, DOI 10.1112/S0024611505015327
- C. Broto, N. Castellana, J. Grodal, R. Levi, and B. Oliver, Extensions of $p$-local finite groups, Trans. Amer. Math. Soc. 359 (2007), no. 8, 3791–3858. MR 2302515, DOI 10.1090/S0002-9947-07-04225-0
- Carles Broto, Ran Levi, and Bob Oliver, The homotopy theory of fusion systems, J. Amer. Math. Soc. 16 (2003), no. 4, 779–856. MR 1992826, DOI 10.1090/S0894-0347-03-00434-X
- Andrew Chermak, Fusion systems and localities, Acta Math. 211 (2013), no. 1, 47–139. MR 3118305, DOI 10.1007/s11511-013-0099-5
- Andrew Chermak, Finite localities I, preprint at http://arxiv.org/abs/1505.07786v3 (2015).
- Andrew Chermak, Finite localities III, preprint at http://arxiv.org/abs/1610.06161v2 (2017).
- A. Chermak and E. Henke, Normal subsystems of fusion systems and partial normal subgroups of localities, preprint at http://arxiv.org/abs/1706.05343v1 (2017).
- David A. Craven, Normal subsystems of fusion systems, J. Lond. Math. Soc. (2) 84 (2011), no. 1, 137–158. MR 2819694, DOI 10.1112/jlms/jdr004
- George Glauberman and Justin Lynd, Control of fixed points and existence and uniqueness of centric linking systems, Invent. Math. 206 (2016), no. 2, 441–484. MR 3570297, DOI 10.1007/s00222-016-0657-5
- Ellen Henke, Minimal fusion systems with a unique maximal parabolic, J. Algebra 333 (2011), 318–367. MR 2785951, DOI 10.1016/j.jalgebra.2010.11.006
- Ellen Henke, Direct and central products of localities, J. Algebra 491 (2017), 158–189. MR 3699092, DOI 10.1016/j.jalgebra.2017.07.028
- Radha Kessar and Markus Linckelmann, $ZJ$-theorems for fusion systems, Trans. Amer. Math. Soc. 360 (2008), no. 6, 3093–3106. MR 2379788, DOI 10.1090/S0002-9947-08-04275-X
- Hans Kurzweil and Bernd Stellmacher, The theory of finite groups, Universitext, Springer-Verlag, New York, 2004. An introduction; Translated from the 1998 German original. MR 2014408, DOI 10.1007/b97433
- Markus Linckelmann, Introduction to fusion systems, Group representation theory, EPFL Press, Lausanne, 2007, pp. 79–113. MR 2336638
- U. Meierfrankenfeld and B. Stellmacher, Applications of the FF-Module Theorem and related results, J. Algebra 351 (2012), 64–106. MR 2862199, DOI 10.1016/j.jalgebra.2011.10.028
- Bob Oliver, Extensions of linking systems and fusion systems, Trans. Amer. Math. Soc. 362 (2010), no. 10, 5483–5500. MR 2657688, DOI 10.1090/S0002-9947-2010-05022-6
- Bob Oliver, Existence and uniqueness of linking systems: Chermak’s proof via obstruction theory, Acta Math. 211 (2013), no. 1, 141–175. MR 3118306, DOI 10.1007/s11511-013-0100-3
- Bob Oliver and Joana Ventura, Extensions of linking systems with $p$-group kernel, Math. Ann. 338 (2007), no. 4, 983–1043. MR 2317758, DOI 10.1007/s00208-007-0104-4
Additional Information
- Ellen Henke
- Affiliation: Institute of Mathematics, University of Aberdeen, Fraser Noble Building, Aberdeen AB24 3UE, United Kingdom
- MR Author ID: 911136
- Email: ellen.henke@abdn.ac.uk
- Received by editor(s): March 16, 2017
- Received by editor(s) in revised form: August 25, 2017
- Published electronically: October 26, 2018
- Additional Notes: For part of this research, the author was supported by the Danish National Research Foundation through the Centre for Symmetry and Deformation (DNRF92).
- © Copyright 2018 American Mathematical Society
- Journal: Trans. Amer. Math. Soc. 371 (2019), 3325-3373
- MSC (2010): Primary 20D20, 20J05, 55P60
- DOI: https://doi.org/10.1090/tran/7388
- MathSciNet review: 3896114