| ⊦ reachable-n(H, n + 1, r, r0) ↔ reachable-1(H, r, H[r].nxt) ∧ reachable-n(H, n, H[r].nxt, r0) |
⊦ reachable-n(H, n + 1, r, r0) ↔ (∃ r1. reachable-1(H, r, r1) ∧ reachable-n(H, n, r1, r0))
⊦ (∃ r1. reachable-1(H, r, r1) ∧ reachable-n(H, n, r1, r0)) ↔ reachable-1(H, r, H[r].nxt) ∧ reachable-n(H, n, H[r].nxt, r0)
Used terms: r0, r, n, H