Abstract:
An involution v of a group G is said to be finite (in G) if vvg has finite order for any v∈G. A subgroup B of G is called a strongly embedded (in G) subgroup if B and G∖B contain involutions, but B∩Bg does not, for any g∈G∖B.
We prove the following results.
Theorem 1. Let a group G contain a finite involution and an involution whose centralizer in G is periodic. If every finite subgroup of G of even order is contained in a simple subgroup isomorphic, for some m, to L2(2m) or Sz(2m), then G is isomorphic to L2(Q) or Sz(Q) for some locally finite field Q of characteristic two. In particular, G is locally finite. Theorem 2. Let a group G contain a finite involution and a strongly embedded subgroup. If the centralizer of some involution in G is a 2-group, and every finite subgroup of even order in G is contained in a finite non-Abelian simple subgroup of G, then G is isomorphic to L2(Q) or Sz(Q) for some locally finite field Q of characteristic two.
Citation:
D. V. Lytkina, V. D. Mazurov, “Groups containing a strongly embedded subgroup”, Algebra Logika, 48:2 (2009), 190–202; Algebra and Logic, 48:2 (2009), 108–114