| validref(str, r, ty, st), validref(str, r, ty, st0), ∀ r. ¬ r ∈ st ∧ r ∈ st0 → ¬ junkref(str, r, st0), ∀ r. ¬ r ∈ st0 ∧ r ∈ st1 → ¬ junkref(str, r, st1), ∀ r, ty. validref(str, r, ty, st0) → validref(str, r, ty, st1) ⊦ validref(str, r, ty, st1) |
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (r, ty)]]