ω_1上无限对称群的子群

SUBGROUPS OF INFINITE SYMMETRIC GROUP ON ω_1

用CH,MA证明了对每个小指数子群G≤Sym (ω_1)都存在可数子集X(?)ω_1,使得Sym(ω_1-X)≤G.

Using CH,MA,it is shown that for every small index subgroup G≤ Sym(ω_1),there is a countable subset X(?)ω_1 such that Sym(ω_1-X)≤G.