| ⊦ (∃ r0. (((r => a0 × r0 * ls(r0, x0)) * P))(H)) ↔ (∃ a, y, r0. ((r => a × r0 * ls(r0, y) * P))(H) ∧ a0 ' + x0 = a ' + y), r = null |
∃ r0. (((r => a0 × r0 * ls(r0, x0)) * P))(H) ⊦ r = null, ∃ a, y, r0. ((r => a × r0 * ls(r0, y) * P))(H) ∧ a0 ' + x0 = a ' + y
∃ a, y, r0. ((r => a × r0 * ls(r0, y) * P))(H) ∧ a0 ' + x0 = a ' + y ⊦ r = null, ∃ r0. (((r => a0 × r0 * ls(r0, x0)) * P))(H)