let E be set ; :: thesis: for A being Subset of (E ^omega) holds
( A + = {(<%> E)} iff A = {(<%> E)} )
let A be Subset of (E ^omega); :: thesis: ( A + = {(<%> E)} iff A = {(<%> E)} )
A + = A |^.. 1 by Th50;
hence ( A + = {(<%> E)} iff A = {(<%> E)} ) by Th15; :: thesis: verum