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_1:26
.= A |^.. (1 + 1) by Th75 ;
hence (A + ) ^^ A = A |^.. 2 ; :: thesis: verum