Definition monotone3 T0 T1 T2 (gf: rel3 T0 T1 T2 -> rel3 T0 T1 T2) :=
  forall x0 x1 x2 r r' (IN: gf r x0 x1 x2) (LE: r <3= r'), gf r' x0 x1 x2.

Theorem paco3_mult_strong: forall r, paco3 gf (upaco3 gf r) <3= paco3 gf r.