fact: Definition one : 'I_4 := @Ordinal 4 1 isT.
imports: mathcomp(all_ssreflect ssralg ssrnum fingroup finalg matrix) Reals Lra mathcomp(Rstruct) ssrR Reals_ext realType_ext logb ssr_ext ssralg_ext bigop_ext fdist proba jfdist_cond entropy