proposition: Lemma lt_creal_cst x y : reflect (cst_creal x < cst_creal y)%CR (x < y).
proof: Proof. apply: (iffP idP)=> lt_xy; pose_big_enough i. + apply: (@lt_crealP (y - x) i i); rewrite ?subr_gt0 //=. by rewrite addrCA subrr addr0. + by close. + by rewrite (@creal_lt_always _ _ i lt_xy). + by close. Qed.
imports: mathcomp.ssreflect.ssreflect mathcomp(ssrfun ssrbool eqtype ssrnat seq choice fintype) mathcomp(bigop order ssralg ssrnum ssrint rat poly polydiv polyorder) mathcomp(perm matrix mxpoly polyXY binomial bigenough)