⊦ r ∈ st .refs ↔ r ∈ st
⊦ r ≠ r0 → (r ∈ addobj(r0, class1, fis, st) ↔ r ∈ st)
⊦ r ∈ addobj(r0, class1, fis, st) ↔ r = r0 ∨ r ∈ st
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, r0)]]