| path(r ' + x, H) ⊦ r = null, x = [], ∃ n. reachable-n(H, n, r, x.last) |
path(r ' + (r0 + x0), H), ∀ r, H. path(r ' + x0, H) → r = null ∨ x0 = [] ∨ (∃ n. reachable-n(H, n, r, x0.last)) ⊦ r0 + x0 = [], r = null, ∃ n. reachable-n(H, n, r, (r0 + x0).last)
Used simplifier rules: reflist freely generated by [], +;;