intros a b; (case a; case b).
intros x c0 x0 c1; generalize c0 c1; case x; case x0; simpl in |- *; auto.
intros c2 c3 H' Q; unfold red in |- *; simpl in |- *; auto.
intros a0 l c2 c3 H' Q; unfold red in |- *; simpl in |- *; auto.
intros a0 l c2 c3 H'; elim H'.
intros a0 l a1 l0 c2 c3 H'; elim H'.
Qed.

Theorem divP_ppc :
forall a b c : poly A0 eqA ltM, divp a b -> divp a c -> divp a (ppcp b c).