fact: Definition SB_val x := let a := (0%N,1%N) in let b := (1%N,0%N) in SB_rec (pair_dist x a b) x a b xH.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype order bigop ssralg) mathcomp(div ssrnum ssrint rat prime path binomial) mathcomp(tuple finset) gaia(fibm)