let E be set ; :: thesis: for A, B being Subset of (E ^omega) holds (A +) \/ (B +) c= (A \/ B) +
let A, B be Subset of (E ^omega); :: thesis: (A +) \/ (B +) c= (A \/ B) +
A1: A + = A |^.. 1 by Th50;
A2: B + = B |^.. 1 by Th50;
(A \/ B) + = (A \/ B) |^.. 1 by Th50;
hence (A +) \/ (B +) c= (A \/ B) + by A1, A2, Th45; :: thesis: verum