| ¬(lastn(8, bits) ≠ [] ∧ (lastn(8, bits).first ↔ ¬ false)), firstn(# bits - 8, bits) + lastn(8, bits) = bits, 8 < # bits, b2i(i2b(bits2int(lastn(8, bits)))) < 0, ∀ bits0. # bits0 < # bits → true → bits0 = [] ∨ sgn(bytes2bits(bits2bytes(bits0))) = sgn(bits0) ⊦ bits = [], false ' + byte2bits(i2b(bits2int(lastn(8, bits)))) = sgn(false ' + lastn(8, bits)), true ∈ bytes2bits(bits2bytes(firstn(# bits - 8, bits))), true ∈ firstn(# bits - 8, bits) |
firstn(# bits - 8, bits) + lastn(8, bits) = bits, 8 < # bits, b2i(i2b(bits2int(lastn(8, bits)))) < 0, ∀ bits0. # bits0 < # bits → true → bits0 = [] ∨ sgn(bytes2bits(bits2bytes(bits0))) = sgn(bits0) ⊦ bits = [], false ' + byte2bits(i2b(bits2int(lastn(8, bits)))) = sgn(false ' + lastn(8, bits)), true ∈ bytes2bits(bits2bytes(firstn(# bits - 8, bits))), true ∈ firstn(# bits - 8, bits), lastn(8, bits).first
Used simplifier rules: ⊦ lastn(n, bits) = [] ↔ n = 0;