intros a b c d; case a; case b; case c; case d; simpl in |- *; auto.
intros a1 m1 a2 m2 a3 m3 a4 m4; intros H1; case H1; intros H2 H3 H4; case H4;
intros H5 H6; split; auto.
rewrite H3; rewrite H6; auto.
Qed.
Hint Resolve eqTerm_multTerm_comp.
Set Implicit Arguments.
Unset Strict Implicit.
Definition invTerm : Term -> Term.
intros H; case H; intros b2 c2; exact (invA b2, c2).
Defined.
Set Strict Implicit.
Unset Implicit Arguments.

Theorem plusTerm_invTerm_zeroP :
forall a : Term, zeroP (plusTerm a (invTerm a)).