| is_valid_ref(str, r, st), st[r -- _type] .type ≤ ty, junkrefs(str, r ', ty, st) ⊦ r = jvmref |
⊦ is_valid_ref(str, r, st) ↔ is_obj(str, r, st) ∨ is_array(str, r, st)
is_obj(str, r, st) ∨ is_array(str, r, st), st[r -- _type] .type ≤ ty, junkrefs(str, r ', ty, st) ⊦ r = jvmref
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, r, str)]]