
theorem
  for S1,S2 being finite non empty ManySortedSign holds S1+*S2 is finite
proof
  let S1,S2 be finite non empty ManySortedSign;
  reconsider C1 = the carrier of S1, C2 = the carrier of S2 as finite set;
  the carrier of S1+*S2 = C1 \/ C2 by Def2;
  hence thesis;
end;
