proposition: Lemma dvdr_addr a b c : b %| a -> (b %| a + c) = (b %| c).
proof: Proof. by move=> ba; rewrite addrC dvdr_addl. Qed.
imports: HB(structures) Coq(ssreflect ssrfun ssrbool Arith.Wf_nat) mathcomp(eqtype ssrnat div seq path) mathcomp(ssralg fintype perm tuple choice generic_quotient) mathcomp(matrix bigop zmodp mxalgebra poly) stronglydiscrete