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