proposition: Fact addNm_subproof : left_inverse zeromor oppmor addmor.
proof: Proof. by move=> x; apply: val_inj; apply: addNr. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat div seq path) mathcomp(ssralg fintype perm choice matrix bigop zmodp mxalgebra poly) ssrcomplements stronglydiscrete coherent edr