theorem Th31:
  op1 ~= op2 iff Name op1 = Name op2
proof
  op2 in Class(the Overloading of S,op1) iff Class(the Overloading of S,
  op1) = Class(the Overloading of S,op2) by EQREL_1:23;
  hence thesis by Th30;
end;
