let E be set ; :: thesis: for A being Subset of
for n being Nat holds (A * ) |^ n c= A *
let A be Subset of ; :: thesis: for n being Nat holds (A * ) |^ n c= A *
let n be Nat; :: thesis: (A * ) |^ n c= A *
(A * ) |^ n c= (A * ) * by Th43;
hence (A * ) |^ n c= A * by Th63; :: thesis: verum