| H[r0] .nxt = null, ∀ n. ∃ r0. reachable-n(H, n, r, r0), reachable(r, r0, H), legal(H), r ∈ H, r0 ∈ H ⊦ r = null |
⊦ reachable(r, r0, H) ↔ r ≠ null ∧ r ∈ H ∧ reachable*(H, r, r0)
H[r0] .nxt = null, ∀ n. ∃ r0. reachable-n(H, n, r, r0), r ≠ null ∧ r ∈ H ∧ reachable*(H, r, r0), legal(H), r ∈ H, r0 ∈ H ⊦ r = null
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (H, r0, r)]]