| st ⊆ st1, validref(str, r, ty, st) ⊦ validref(str, r, ty, st1) |
⊦ validref(str, r, ty, st) ↔ r = jvmref ∨ st[r -- _type] .type ≤ ty ∧ ¬ junkref(str, r, st)
st ⊆ st1, r = jvmref ∨ st[r -- _type] .type ≤ ty ∧ ¬ junkref(str, r, st) ⊦ validref(str, r, ty, st1)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, ty, r, str)]]