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Proof step 4 from proof length-from (previous step)

# x = n0 + n ⊦ #(x from n) = n0

User applied rule structural induction

And obtained the following new goals

Proof step 5:
∀ x, n0. # x = n0 + n1 → #(x from n1) = n0, # x = n0 + n1 +1 ⊦ #(x from n1 +1) = n0

Rule argument

indvar: n

Additional information

Used simplifier rules: from-zero-l: ⊦ x from 0 = x;%nat freely generated by 0, +1;;%add-base: ⊦ n + 0 = n; from specification nat-basic2%a: ⊦ (m + n0) + n1 = m + n0 + n1; from specification nat-basic2%c: ⊦ m + n = n + m; from specification nat-basic2