| # x = # rx ⊦ dls(head, prev, x + a ', rx + tail0 ', next, tail) = _∃(λ r. ⌜tail0 = tail⌝ ∧ tail => mkcell(r, next, a) * dls(head, prev, x, rx, tail, r)) |
⊦ P0 = P1 ↔ (∀ P, H. ((P0 * P))(H) ↔ ((P1 * P))(H))
[Concretesimprules(()), Extraterms((_∃ (λ r. ⌜tail0 = tail⌝ ∧ tail => mkcell(r, next, a) * dls(head, prev, x, rx, tail, r)) dls(head, prev, x + a ', rx + tail0 ', next, tail)))]