proposition: Fact addmor_proof phi1 phi2 : pres N %| pres M *m (phi1%:m + phi2%:m).
proof: Proof. by rewrite mulmxDr dvdmxD // dvdmx_morphism. 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