| ¬(bits0 ≠ [] ∧ bits = true '), ∀ bits1, bits. # bits1 < # bits0 → true → bits = [] ∨ bits1 = [] ∨ bitsand(bits, bits1) = bitsand(bits1, bits) ⊦ bitsand(bits, bits0) = bitsand(bits0, bits), bits0 = [], bits = [], bits0 = true ', bits0 = false ', bits ≠ bits.first ' ∧ bits0 ≠ bits0.first ' |
∀ bits1, bits. # bits1 < # bits0 → true → bits = [] ∨ bits1 = [] ∨ bitsand(bits, bits1) = bitsand(bits1, bits) ⊦ bitsand(bits, bits0) = bitsand(bits0, bits), bits0 = [], bits = [], bits0 = true ', bits0 = false ', bits = true ', bits ≠ bits.first ' ∧ bits0 ≠ bits0.first '