fact: Definition fhrel_ldv (e1 : {fhrel A & B}) (e2 : {fhrel A & C}) : {fhrel B & C} := fun i j => [forall k, e1 k i ==> e2 k j].
imports: Setoid Morphisms kat normalisation rewriting kat_tac comparisons rel relalg boolean mathcomp(all_ssreflect)