src/HOL/Tools/Nitpick/nitpick_kodkod.ML

          | Op2 (Less, T, Formula polar, u1, u2) =>
            formula_from_opt_atom polar bool_j0
                (to_r (Op2 (Less, T, Opt bool_atom_R, u1, u2)))
          | Op2 (Subset, _, _, u1, u2) =>
            let
-             val dom_T = elem_type (type_of u1)
+             val dom_T = pseudo_domain_type (type_of u1)
              val R1 = rep_of u1
              val R2 = rep_of u2
              val (dom_R, ran_R) =
                case min_rep R1 R2 of
                  Func Rp => Rp