| ∀ 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 = [] |
⊦ 1 < # bits ∧ 1 < # bits0 → bitsand(bits, bits0) = bitsand(bits.butlast, bits0.butlast) + (bits.last ∧ bits0.last)
¬(1 < # bits ∧ 1 < # bits0), ∀ 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 = []
1 < # bits ∧ 1 < # bits0, ∀ bits1, bits. # bits1 < # bits0 → true → bits = [] ∨ bits1 = [] ∨ sgn(bitsand(sgn(bits), bits1)) = sgn(bitsand(bits, bits1)) ⊦ sgn(bitsand(sgn(bits), bits0)) = sgn(bitsand(bits.butlast, bits0.butlast) + (bits.last ∧ bits0.last)), bits0 = [], bits = []
Used terms: bits0, bits