| legal(H), r ∈ H ⊦ r = null, ∃ r0. reachable(r, r0, H) ∧ H[r0] .nxt = null, ∃ r0. reachable-n(H, n, r, r0) |
∀ H, r. legal(H) ∧ r ∈ H → r = null ∨ (∃ r0. reachable(r, r0, H) ∧ H[r0] .nxt = null) ∨ (∃ r0. reachable-n(H, n0, r, r0)), legal(H), r ∈ H ⊦ r = null, ∃ r0. reachable(r, r0, H) ∧ H[r0] .nxt = null, ∃ r0. reachable-n(H, n0 +1, r, r0)
[[CONCRETESIMPRULES : ([CSIMPGEN : nat generated by 0, +1;], [CSIMPSEQ : ⊦ reachable-n(H, 0, r, r0) ↔ r = r0])]]