| x ≠ [], ce.nxt = H[H[r0].nxt].nxt, x.last = H[r0].nxt, path(r ' + x, H[r0, ce]), reachable(r, r0, H), H[r0].nxt ∈ H, H[r0].nxt ∈ H[r0, ce], r0 ∈ H, ∀ r1. ¬ reachable(H[r1].nxt, r1, H) ⊦ H[r0].nxt = null, r ∈ x, dups(x) |
ce.nxt = H[x.last].nxt, x.last = H[r0].nxt, path(r ' + x, H[r0, ce]), reachable(r, r0, H), x.last ∈ H, x.last ∈ H[r0, ce], r0 ∈ H, ∀ r1. ¬ reachable(H[r1].nxt, r1, H) ⊦ x.last = null, x = [], r ∈ x, dups(x)