Used simplifier rules: pe: ⊦ n ≠ 0 → m + n -1 = (m + n)-1;%pred: ⊦ (m + 1)-1 = m;%a: ⊦ (m + n0) + n1 = m + n0 + n1;%c: ⊦ m + n = n + m; Used terms: m -1