reserve I,X,x,d,i for set;
reserve M for ManySortedSet of I;
reserve EqR1,EqR2 for Equivalence_Relation of X;
reserve I for non empty set;
reserve M for ManySortedSet of I;
reserve EqR,EqR1,EqR2,EqR3,EqR4 for Equivalence_Relation of M;

theorem
  EqR "\/" EqR = EqR
proof
  for EqR3 st EqR (\/) EqR c= EqR3 holds EqR c= EqR3;
  hence thesis by Th6;
end;
