theorem
  for X,Y,Z for y being Element of Y, F being (Function of X,Y),
      G being Function of Y,Z holds F"{y} c= (G*F)"{G.y}
proof
  let X,Y,Z;
  let y be Element of Y, F be (Function of X,Y), G be Function of Y,Z;
  F"{y} c= (G*F)"Im(G,y) by FUNCT_2:44;
  hence thesis by SETWISEO:8;
end;
