reserve S for non empty non void ManySortedSign,
  A for MSAlgebra over S;
reserve A for non-empty MSAlgebra over S;
reserve S for non empty non void ManySortedSign,
  A for non-empty MSAlgebra over S,
  R for ManySortedRelation of the Sorts of A;

theorem
  for R being invariant ManySortedRelation of A holds InvCl R = R
proof
  let R be invariant ManySortedRelation of A;
   InvCl R c= R & R c= InvCl R by Def11;
  hence thesis by PBOOLE:146;
end;
