11 lines
209 B
Text
11 lines
209 B
Text
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open nat
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definition f (a n : ℕ) : ℕ := nat.rec_on n (λa', a') (λn' f' a', f' (a' * 2)) a
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example (a n : nat) : a = 2 → f a (succ n) = f 4 n :=
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begin
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unfold f at {1},
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state,
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intros, subst a
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end
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