intros a b c; case a; case b; case c; unfold ltT in |- *; simpl in |- *; auto.
Qed.

Theorem invTerm_ltT_l : forall a c, ltT a c -> ltT (invTerm invA a) c.
intros a b; case a; case b; unfold ltT in |- *; simpl in |- *; auto.