intros a b c; (case a; case b; case c).
intros x c0 x0 c1 x1 c2; generalize c0 c1 c2; case x; case x0; case x1;
simpl in |- *; auto.
intros a0 l a1 l0 a2 l1 H' H'0 H'1 H'2.
apply divP_eqTerm_comp with (1 := cs) (a := ppc (A:=A) A1 (n:=n) a0 a1); auto.
Qed.

Theorem zerop_ddivp_ppc :
forall a b : poly A0 eqA ltM, ~ zerop a -> ~ zerop b -> divp (ppcp a b) b.