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