Definition buch : list (poly A0 eqA ltM) -> list (poly A0 eqA ltM).

Theorem imp_in : forall (P : list (poly A0 eqA ltM)) (a : list (Term A n)), inPolySet A A0 eqA n ltM a P -> exists b : poly A0 eqA ltM, In b P /\ a = s2p A A0 eqA n ltM b.