
theorem
  for S being non empty ManySortedSign holds S+*S = the ManySortedSign of S
proof
  let S be non empty ManySortedSign;
A1: the carrier' of S = (the carrier' of S) \/ the carrier' of S;
A2: the Arity of S = (the Arity of S)+*the Arity of S;
A3: the ResultSort of S = (the ResultSort of S)+*the ResultSort of S;
  the carrier of S = (the carrier of S) \/ the carrier of S;
  hence thesis by A1,A2,A3,Def2;
end;
