摘要
Let F (X) (A(X)) be the free (Abelian) topological group over X. We prove: If P is one of the spaces R, Q, R \ Q, βω, βω \ ω and 2κ for an infinite κ and ifF (X) or A(X) contains a copy of P, then X contains a copy of P. If P is the one-point compactification of an infinite discrete space or ω1 + 1, this is not true. If P = ω1, this holds for F(X) but is independent of ZFC for A(X).