proposition: Lemma fdist_proj13_AC (R : realType) (A B C : finType) (P : R.-fdist (A * B * C)) : fdist_proj13 (fdistAC P) = P`1.
proof: Proof. rewrite /fdist_proj13 /fdist_snd /fdistA /fdistC12 /fdistAC /fdist_fst. rewrite !fdistmap_comp /=; congr (fdistmap _ _). by rewrite boolp.funeqE => -[[]]. Qed.
imports: mathcomp(all_ssreflect ssralg fingroup perm matrix) mathcomp(all_algebra vector reals normedtype) mathcomp(mathcomp_extra boolp) mathcomp(Rstruct) ssrR logb realType_ext ssr_ext ssralg_ext bigop_ext