| NCic.Rel i -> [Bound (i, arity)]
| NCic.Sort (NCic.Prop) -> assert (arity=0); [Proposition]
| NCic.Sort _ -> assert (arity=0); [Datatype]
| NCic.Rel i -> [Bound (i, arity)]
| NCic.Sort (NCic.Prop) -> assert (arity=0); [Proposition]
| NCic.Sort _ -> assert (arity=0); [Datatype]