| bits0 ≠ [] ∧ (bits0.first ↔ boolvar), n ≤ # sgn(bits0), ∀ n0. ¬ # sgn(bits0) < n0 → bits0 = [] ∨ lastn(n0, sgn(bits0)) = lastn(n0, bits0) ⊦ lastn(n, sgn(bits0)) = lastn(n, boolvar ' + bits0) |
n ≤ # sgn(bits0), ∀ n0. ¬ # sgn(bits0) < n0 → lastn(n0, sgn(bits0)) = lastn(n0, bits0) ⊦ lastn(n, sgn(bits0)) = lastn(n, bits0.first ' + bits0), bits0 = []