theorem
  g (/) c1 (/) c2 = g (/) (c1*c2)
proof
  dom(g(/)c1) = dom g & dom(g(/)(c1*c2)) = dom g by VALUED_1:def 5;
  hence dom(g(/)c1(/)c2) = dom(g(/)(c1*c2)) by VALUED_1:def 5;
  let x be object;
  assume x in dom(g(/)c1(/)c2);
  thus (g(/)c1(/)c2).x = (g(/)c1).x * c2" by VALUED_1:6
    .= g.x * c1" * c2" by VALUED_1:6
    .= g.x * (c1" * c2")
    .= g.x * (c1*c2)" by XCMPLX_1:204
    .= (g(/)(c1*c2)).x by VALUED_1:6;
end;
