proposition: Lemma fgaddA : associative fgadd.
proof: Proof. by move=> x y z; apply/malgP=> k; rewrite !fgaddE addrA. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq path choice finset fintype finfun) mathcomp(tuple bigop ssralg ssrint ssrnum) xfinmap