intros a b H'.
apply (eqT_trans A n) with (y := b); auto.
apply (eqT_trans A n) with (y := multTerm (A:=A) multA (n:=n) (T1 A1 n) b);
auto.
apply (T1_eqT A A1 eqA); auto.
Qed.
Hint Resolve invTerm_eqT_comp invTerm_T1_eqT_comp
multTerm_invTerm_T1_eqT_comp.

(* Specifications: *)
Lemma minusP_is_plusP_mults :
forall p q r : list (Term A n),
minusP p q r ->
eqP A eqA n r
(pluspf (A:=A) A0 (eqA:=eqA) plusA eqA_dec (n:=n) (ltM:=ltM) ltM_dec p
(mults (A:=A) multA (n:=n) (invTerm (A:=A) invA (n:=n) (T1 A1 n)) q)).