fact: Fixpoint symfn (k : nat) (p : {mpoly R[n]}) := if k is k'.+1 then let (t1, p) := symf1 p in let (t2, p) := symfn k' p in (t1 + t2, p) else symf1 p.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finfun bigop finset binomial) mathcomp(order fingroup perm ssralg zmodp poly ssrint) mathcomp(matrix vector) mathcomp(bigenough) ssrcomplements freeg