proposition: Lemma dE abc : d abc = \sum_(x in D) P (abc.1.1, abc.1.2, x, abc.2).
proof: Proof. case: abc => [[a b] c] /=. rewrite /d fdistXE fdist_sndE; apply eq_bigr => d _. by rewrite fdistAE /= fdistXE fdistAE. Qed.
imports: mathcomp(all_ssreflect ssralg matrix) Reals mathcomp(Rstruct) ssrR Reals_ext logb ssr_ext ssralg_ext bigop_ext fdist proba jfdist_cond