proposition: Lemma mem0_itvoo_xNx x : 0 \in `](- x), x[ = (0 < x).
proof: Proof. by rewrite itv_boundlr [in LHS]/<=%O /= oppr_lt0 andbb. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(div fintype bigop order ssralg finset fingroup) mathcomp(ssrnum)