| ('5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] ' = "0", m < 5 ⊦ |
⊦ chars ≠ [] ∧ n ≠ 0 → chars[n] = chars.rest[n - 1]
¬('5' ' + '6' ' + '7' ' + '8' ' + '9' ' ≠ [] ∧ m ≠ 0), ('5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] ' = "0", m < 5 ⊦
'5' ' + '6' ' + '7' ' + '8' ' + '9' ' ≠ [] ∧ m ≠ 0, ('5' ' + '6' ' + '7' ' + '8' ' + '9' ').rest[m - 1] ' = "0", m < 5 ⊦
Used terms: m, '5' ' + '6' ' + '7' ' + '8' ' + '9' '