reserve I,X,x,d,i for set;
reserve M for ManySortedSet of I;
reserve EqR1,EqR2 for Equivalence_Relation of X;

theorem Th2:
  EqCl EqR1 = EqR1
proof
  for EqR2 be Equivalence_Relation of X st EqR1 c= EqR2 holds EqR1 c= EqR2;
  hence thesis by Def1;
end;
