| path(r ' + x, H[r0, ce]), r0 ∈ H, (r ' + x).last ∈ H[r0, ce] ⊦ reachable(r, r0, H), reachable(r, (r ' + x).last, H) |
path(r ' + (r1 + x0), H[r0, ce]), (r ' + (r1 + x0)).last ∈ H[r0, ce], r0 ∈ H, ∀ r, H, r0, ce. path(r ' + x0, H[r0, ce]) ∧ r0 ∈ H ∧ (r ' + x0).last ∈ H[r0, ce] → reachable(r, r0, H) ∨ reachable(r, (r ' + x0).last, H) ⊦ reachable(r, (r ' + (r1 + x0)).last, H), reachable(r, r0, H)
Used simplifier rules: path-one: ⊦ path(r ', H) ↔ r ∈ H ∧ r ≠ null;%self-reachable: ⊦ reachable(r, r, H) ↔ r ≠ null ∧ r ∈ H;%reflist freely generated by [], +;;% ⊦ x0 + [] = x0; (s)%a: ⊦ (x0 + x1) + x2 = x0 + x1 + x2; from specification list[reflist]% ⊦ r '.last = r; (s)% ⊦ r ∈ H[r0, ce] ↔ r = r0 ∨ r ∈ H; (ws)