fact: Definition Dijkstra_prop2bis := forall a b, coprime a b.+1 -> exists k, a = s k /\ b.+1 = s k.+1.
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)