intros a b c; case a; case b; case c; simpl in |- *; auto.
intros a0 m a1 m0 a2 m1; split; auto.
apply multA_assoc with (1 := cs); auto.
apply mult_mon_assoc.
Qed.

Theorem multTerm_com :
forall a b : Term, eqTerm (multTerm a b) (multTerm b a).