let E be set ; :: thesis: for A being Subset of (E ^omega) holds (A +) ^^ A = A |^.. 2
let A be Subset of (E ^omega); :: thesis: (A +) ^^ A = A |^.. 2
(A +) ^^ A = (A +) ^^ (A |^ 1) by FLANG_1:25
.= A |^.. (1 + 1) by Th75 ;
hence (A +) ^^ A = A |^.. 2 ; :: thesis: verum