fact: Definition toParamSym@{} : Param2b4.Rel@{i} B A := @Param2b4.BuildRel B A (sym_rel (graph f)) (@Map2b.BuildHas@{i} _ _ _ _ section_in_retract) (@Map4.BuildHas@{i} _ _ _ _ (fun _ _ => id) (fun _ _ => id) (fun _ _ _ => 1%path)).
imports: ssreflect