fact: Definition toParam@{} : Param42b.Rel@{i} A B := @Param42b.BuildRel A B (graph f) (@Map4.BuildHas@{i} _ _ _ _ (fun _ _ => id) (fun _ _ => id) (fun _ _ _ => 1%path)) (@Map2b.BuildHas@{i} _ _ _ _ section_in_retract).
imports: ssreflect