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