| # bits0 ≤ m ⊦ lastn(m, bits + fillsgn(m + 1, bits0).rest) = fillsgn(m, bits0) |
⊦ n ≤ # bits → lastn(n, bits0 + bits) = lastn(n, bits)
¬ m ≤ # fillsgn(m + 1, bits0).rest, # bits0 ≤ m ⊦ lastn(m, bits + fillsgn(m + 1, bits0).rest) = fillsgn(m, bits0)
m ≤ # fillsgn(m + 1, bits0).rest, # bits0 ≤ m ⊦ lastn(m, fillsgn(m + 1, bits0).rest) = fillsgn(m, bits0)
Used terms: fillsgn(m + 1, bits0).rest, bits, m