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