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Proof step 60 from proof natstring-chars (previous step)

10 ≤ m, char ∈ n→s(m / 10), ∀ m1, char. m1 < m → char ∈ n→s(m1) → char = '0' ∨ char = '9' ∨ char = '8' ∨ char = '7' ∨ char = '6' ∨ char = '5' ∨ char = '4' ∨ char = '3' ∨ char = '2' ∨ char = '1' ⊦ char = '1', char = '2', char = '3', char = '4', char = '5', char = '6', char = '7', char = '8', char = '9', char = '0', m = 0, char ∈ n→s(m % 10)

User applied rule apply induction

And closed the goal!

Rule argument

subst: [m1, char] → [m / 10, char]

Additional information

Used simplifier rules: ⊦ ¬ m < n ↔ n ≤ m;%m0 ≠ 0 ⊦ n ≤ m / m0 ↔ n * m0 ≤ m;% ⊦ n ≠ 0 → (m * n ≤ n ↔ m ≤ 1);% ⊦ m0 * m * n = (m0 * m) * n;% ⊦ m * n = n * m; Used terms: m / 10, char