Covering the symmetric groups with proper subgroups

نویسنده

  • Attila Maróti
چکیده

Let G be a group that is a set-theoretic union of finitely many proper subgroups. Cohn defined σ(G) to be the least integer m such that G is the union of m proper subgroups. Tomkinson showed that σ(G) can never be 7, and that it is always of the form q +1 (q a prime power) for solvable groups G. In this paper we give exact or asymptotic formulas for σ(Sn). In particular, we show that σ(Sn) ≤ 2n−1, while for alternating groups we find σ(An) ≥ 2n−2 unless n = 7 or 9. An application of this result is also given.

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عنوان ژورنال:
  • J. Comb. Theory, Ser. A

دوره 110  شماره 

صفحات  -

تاریخ انتشار 2005