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