| r ∈ H, legal(H), reachable-n(H, m + 1, r, r0) ⊦ H[r0] .nxt = null, r = null, r0 ≠ null ∧ r0 ∈ H |
⊦ reachable-n(H, n + 1, r, r0) ↔ (∃ r1. reachable-n(H, n, r, r1) ∧ reachable-1(H, r1, r0))
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ reachable-1(H, r, r0) ↔ r ≠ null ∧ r0 ≠ null ∧ r ∈ H ∧ r0 ∈ H ∧ H[r] .nxt = r0])], [EXTRATERMS : (r0, r, m, H)]]