| H[r0] .nxt = null, legal(H), r ∈ H, reachable-n(H, n0, r, r0) ⊦ r = null, r ≠ null ∧ r ∈ H ∧ reachable*(H, r, r0), ∃ r0. reachable(r, r0, H) ∧ H[r0] .nxt = null |
⊦ reachable*(H, r, r0) ↔ (∃ n. reachable-n(H, n, r, r0))
H[r0] .nxt = null, legal(H), r ∈ H, reachable-n(H, n0, r, r0) ⊦ r = null, r ≠ null ∧ r ∈ H ∧ (∃ n. reachable-n(H, n, r, r0)), ∃ r0. reachable(r, r0, H) ∧ H[r0] .nxt = null
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (r0, r, H)]]