Abstract
Let G be a permutation group on a set Ω. A subset B of Ω is a base for G if the pointwise stabilizer of B in G is trivial; the base size of G is the minimal cardinality of a base for G, denoted by b(G). In this paper we calculate the base size of every primitive almost simple classical group with point stabilizer in Aschbacher’s collection S of irreducibly embedded almost simple subgroups. In this situation we also establish strong asymptotic results on the probability that randomly chosen subsets of Ω form a base for G. Indeed, with some specific exceptions, we show that almost all pairs of points in Ω are bases.
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The authors would like to thank Dr. T. Breuer for his assistance with a computer calculation (see Lemma 5.5). They also thank Dr. C. Roney-Dougal for supplying the list of subgroups in S in the low dimensional classical groups (see Table 14), which is taken from the forthcoming book [7]. The first author was supported by EPSRC grant EP/I019545/1. The second author was partially supported by NSF grant DMS-1001962 and by Simons Foundation Fellowship 224965.
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Burness, T.C., Guralnick, R.M. & Saxl, J. Base sizes for S-actions of finite classical groups. Isr. J. Math. 199, 711–756 (2014). https://doi.org/10.1007/s11856-013-0059-y
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DOI: https://doi.org/10.1007/s11856-013-0059-y