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

Theorem nf_red : forall (a : poly A0 eqA ltM) (aP aQ : list (poly A0 eqA ltM)), incl aP aQ -> red (nf a aP) aQ -> red a aQ.