intros a b; case a; case b; simpl in |- *; auto.
intuition.
apply (eqA_trans _ _ _ _ _ _ _ _ _ cs) with (y := a1); auto;
apply (eqA_sym _ _ _ _ _ _ _ _ _ cs); auto.
Qed.

Theorem nzeroP_comp_eqTerm :
forall a b : Term, ~ zeroP a -> eqTerm a b -> ~ zeroP b.