reserve V, C for set;
reserve A, B, D for Element of Fin PFuncs (V, C);
reserve s for Element of PFuncs (V,C);

theorem
  for K be Element of SubstitutionSet (V, C) holds mi (K^K) = K
proof
  let K be Element of SubstitutionSet (V, C);
  thus mi (K^K) = mi K by Th24
    .= K by Th11;
end;
