fact: Definition rel_prod (X Y : Rel) : Rel := ⦑πl X × πl Y, πr X × πr Y | fun p1 p2 => X (nfst p1) (nfst p2) × Y (nsnd p1) (nsnd p2)|TyRel⦒.
imports: Coq(ssreflect ssrfun ssrbool) Coq(Relation_Definitions Morphisms) Mon(SPropBase) Relational(Category RelativeMonads EnrichedSetting)