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Proof step 20 from proof bitsor-zeroes-false (previous step)

# bits2 ≤ # bits1, ∀ bits1, bits0. # bits0 < #(bits2 + false ') → # bits0 ≤ 1 + # bits1 → bits0 = [] ∨ bitsor(bits0, false ' + bits1) = false ' + bits1 ∨ true ∈ bits0 ⊦ bits1 = [], bits2 = [], bitsor(bits2, false ' + bits1.butlast) + bits1.last ' = false ' + bits1, true ∈ bits2

User applied rule insert elim lemma

And obtained the following new goals

Proof step 21:
bits1 = bits + boolvar ', # bits2 ≤ # bits1, ∀ bits1, bits0. # bits0 < #(bits2 + false ') → # bits0 ≤ 1 + # bits1 → bits0 = [] ∨ bitsor(bits0, false ' + bits1) = false ' + bits1 ∨ true ∈ bits0 ⊦ bits1 = [], bits2 = [], bitsor(bits2, false ' + bits) + boolvar ' = false ' + bits1, true ∈ bits2

Rule argument

seq: bits ≠ [] ⊦ (boolvar ↔ bits.last) ∧ bits0 = bits.butlast ↔ bits = bits0 + boolvar ' subst: [bits, boolvar, bits0] → [bits1, boolvar, bits] rotate: T spec: list-last inst: bitlista name: last-elim

Additional information

Used simplifier rules: bits ≠ [] ⊦ (boolvar ↔ bits.last) ∧ bits0 = bits.butlast ↔ bits = bits0 + boolvar '; (elim) Used terms: bits1, boolvar, bits