proposition: Lemma inj_f : injective f.
proof: Proof. by rewrite /f => -[[[? ?] ?] ?] [[[? ?] ?] ?] /= [-> -> -> ->]. Qed.
imports: mathcomp(all_ssreflect ssralg matrix) Reals mathcomp(Rstruct) ssrR Reals_ext logb ssr_ext ssralg_ext bigop_ext fdist proba jfdist_cond