| is_obj(r0, st), has_reffield(r0, st -- r) ⊦ r0 = r, has_reffield(r0, st) |
⊦ is_obj(r, st) → (has_reffield(r, st) ↔ (∃ fs. fs ' ∈ instfields(st[r -- _type] .type .class) ∧ is_reftype(fs .type)))
⊦ r ≠ r0 → (is_obj(r0, st -- r) ↔ is_obj(r0, st))
is_obj(r0, st -- r), is_obj(r0, st), ∃ fs. fs ' ∈ instfields((st -- r)[r0 -- _type] .type .class) ∧ is_reftype(fs .type) ⊦ r0 = r, has_reffield(r0, st)
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st -- r, r0)]]