| r ∈ H, legal(H), reachable-n(H, n, r, r0) ⊦ r = null, (∀ r1. ¬ reachable-n(H, n, r, r1) ∨ ¬ reachable-1(H, r1, H[r0] .nxt)) ↔ H[r0] .nxt = null |
∀ r1. ¬ reachable-n(H, n, r, r1) ∨ ¬ reachable-1(H, r1, H[r0] .nxt), r ∈ H, legal(H), reachable-n(H, n, r, r0) ⊦ H[r0] .nxt = null, r = null
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ reachable-1(H, r, r0) ↔ r ≠ null ∧ r0 ≠ null ∧ r ∈ H ∧ r0 ∈ H ∧ H[r] .nxt = r0])]]