| m ≤ n, m ≤ # asar ⊦ union(asar[n, as], 0, m) = union(asar, 0, m) |
m0 +1 ≤ # asar, m0 +1 ≤ n, ∀ n, asar, as. m0 ≤ n ∧ m0 ≤ # asar → union(asar[n, as], 0, m0) = union(asar, 0, m0) ⊦ union(asar[n, as], 0, m0 +1) = union(asar, 0, m0 +1)
Used simplifier rules: union-base: ⊦ union(asar, n, 0) = ∅;%nat freely generated by 0, +1;;