intros a b nZa nZb; apply ppcm0; auto.
intros r H'1 H'2; inversion H'1; inversion H'2.
cut (~ zeroP (A:=A) A0 eqA (n:=n) (ppc a b)); [ intros nZppab | auto ].
apply divTerm_def with (nZb := nZppab); auto.
apply divTerm_ppc with (nZa := nZa) (nZb := nZb); auto.
apply ppc_nZ; auto.
apply divTerm_def with (nZb := nZa); auto.
apply ppc_nZ; auto.
apply divTerm_ppcl; auto.
apply divTerm_def with (nZb := nZb); auto.
apply ppc_nZ; auto.
apply divTerm_ppcr; auto.
Qed.

Theorem ppc_multTerm_divP :
forall a b : Term A n,
~ zeroP (A:=A) A0 eqA (n:=n) a ->
~ zeroP (A:=A) A0 eqA (n:=n) b ->
divP (multTerm (A:=A) multA (n:=n) a b) (ppc a b).