| m0 < 7, ∀ m1, char. m1 < ((m0 + 1) + 1) + 1 → char ∈ n→s(m1) → char = '0' ∨ char = '9' ∨ char = '8' ∨ char = '7' ∨ char = '6' ∨ char = '5' ∨ char = '4' ∨ char = '3' ∨ char = '2' ∨ char = '1' ⊦ m0 = 0, ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '0', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '9', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '8', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '7', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '6', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '5', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '4', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '3', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '2', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m0 - 1] = '1' |
m0 = m + 1, m0 < 7, ∀ m1, char. m1 < ((m0 + 1) + 1) + 1 → char ∈ n→s(m1) → char = '0' ∨ char = '9' ∨ char = '8' ∨ char = '7' ∨ char = '6' ∨ char = '5' ∨ char = '4' ∨ char = '3' ∨ char = '2' ∨ char = '1' ⊦ m0 = 0, ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '0', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '9', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '8', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '7', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '6', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '5', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '4', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '3', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '2', ('4' ' + '5' ' + '6' ' + '7' ' + '8' ' + '9' ')[m] = '1'
Used simplifier rules: n ≠ 0 ⊦ m = n - 1 ↔ n = m + 1; (elim) Used terms: m0, m