 reserve X, Y for set, A for Ordinal;
 reserve z,z1,z2 for Complex;
 reserve r,r1,r2 for Real;
 reserve q,q1,q2 for Rational;
 reserve i,i1,i2 for Integer;
 reserve n,n1,n2 for Nat;

theorem
  for X being rational-membered set
  holds [q1,q2] in multRel(X,q) iff q1 in X & q2 in X & q2 = q * q1 by Th42;
