m0 = m + 1, ('5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] ' = "0", m0 < 6 ⊦ m0 = 0
Used simplifier rules: n ≠ 0 ⊦ m = n - 1 ↔ n = m + 1; (elim) Used terms: m0, m