proposition: Fact polyOver_addr_closed : addr_closed (polyOver S).
proof: Proof. split=> [|p q Sp Sq]; first exact: polyOver0. by apply/polyOverP=> i; rewrite coefD rpredD ?(polyOverP _). Qed.
imports: HB(structures) mathcomp(ssreflect ssrbool ssrfun eqtype ssrnat seq choice) mathcomp(fintype bigop finset tuple) mathcomp(div ssralg countalg binomial)