proposition: Lemma cpr_eq_pairA a b c d : `Pr[ [% TX, [% TY, TZ]] = (a, (b, c)) | TW = d ] = `Pr[ [% TX, TY, TZ] = (a, b, c) | TW = d].
proof: Proof. rewrite 2!cpr_eqE'; congr (Pr _ _ / _). by apply/setP => u; rewrite !inE /= !xpair_eqE andbA. Qed.
imports: mathcomp(all_ssreflect ssralg ssrnum matrix) mathcomp(Rstruct reals) Reals Lra ssrR Reals_ext realType_ext logb ssr_ext ssralg_ext bigop_ext fdist