| ¬ true ∈ firstn(# bits - 8, bits) ∧ firstn(# bits - 8, bits) ≠ [], firstn(# bits - 8, bits) + lastn(8, bits) = bits, 8 < # bits, ∀ bits0. # bits0 < # bits → true → bits0 = [] ∨ sgn(bytes2bits(bits2bytes(bits0))) = sgn(bits0) ⊦ bits = [], sgn(false ' + byte2bits(i2b(bits2int(lastn(8, bits))))) = sgn(false ' + lastn(8, bits)), true ∈ firstn(# bits - 8, bits), true ∈ bytes2bits(bits2bytes(firstn(# bits - 8, bits))) |
firstn(# bits - 8, bits) + lastn(8, bits) = bits, 8 < # bits, ∀ bits0. # bits0 < # bits → true → bits0 = [] ∨ sgn(bytes2bits(bits2bytes(bits0))) = sgn(bits0) ⊦ bits = [], sgn(false ' + byte2bits(i2b(bits2int(lastn(8, bits))))) = sgn(false ' + lastn(8, bits)), true ∈ bytes2bits(bits2bytes(firstn(# bits - 8, bits))), true ∈ firstn(# bits - 8, bits)
Used simplifier rules: ⊦ n < m → m - n ≠ 0;% ⊦ firstn(n, bits) = [] ↔ n = 0;