reserve c,c1,c2,x,y,z,z1,z2 for set;
reserve C1,C2,C3 for non empty set;

theorem
  for f be RMembership_Func of C1,C1 holds f(#)Zmf(C1,C1) = Zmf(C1,C1) (#)f
proof
  let f be RMembership_Func of C1,C1;
  f(#)Zmf(C1,C1) = Zmf(C1,C1) by Th23;
  hence thesis by Th22;
end;
