| r2 ≠ null ⊦ H[r2] = a × null → ( ¬ ¬ (ll-trav(r0, r1, r2, x) * P)(H) ↔ x ≠ [] ∧ (r1 = null ⊃ (r0 = r2 ∧ (lls(r0, null, x) * P)(H)); (∃ y, b. x = y + (b + a) ∧ (lls(r0, r1, y) * r1 => b × r2 * r2 => a × null * P)(H)))) |
H[r2] = a × null ⊦ r2 = null, (ll-trav(r0, r1, r2, x) * P)(H) ↔ x ≠ [] ∧ (r1 = null ⊃ (r0 = r2 ∧ (lls(r2, null, x) * P)(H)); (∃ y, b. x = y + b ' + a ' ∧ (lls(r0, r1, y) * r1 => b × r2 * r2 => a × null * P)(H)))
[[CONCRETESIMPRULES : ([CSIMPSEQ : ⊦ a + b = a ' + b '])]]