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