let E, x be set ; :: thesis: for A being Subset of (E ^omega) holds
( <%x%> in A + iff <%x%> in A )
let A be Subset of (E ^omega); :: thesis: ( <%x%> in A + iff <%x%> in A )
A + = A |^.. 1 by Th50;
hence ( <%x%> in A + iff <%x%> in A ) by Th46; :: thesis: verum