⊦ r ∈ st ↔ (∃ sk. r -- sk ∈ st)
∃ sk. r0 -- sk ∈ st, ∀ rk. rk ∈ st → rk .ref ≠ r0 ⊦ r0 = jvmref
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, r0)]]