| st ⊆ st0, validref(str, r, ty, st0) ⊦ junkref(str, r, st), validref(str, r, ty, st) |
⊦ validref(str, r, ty, st) ↔ r = jvmref ∨ st[r -- _type] .type ≤ ty ∧ ¬ junkref(str, r, st)
st ⊆ st0, r = jvmref ∨ st0[r -- _type] .type ≤ ty ∧ ¬ junkref(str, r, st0) ⊦ junkref(str, r, st), validref(str, r, ty, st)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st0, ty, r, str)]]