16 lines
290 B
Text
16 lines
290 B
Text
@[irreducible] def f : nat → nat
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| 0 := 1
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| (n+1) := 2 * f n
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lemma ex1 (n : nat) : f (n+1) = 2 * f n :=
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begin
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fail_if_success {refl},
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simp only [f]
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end
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lemma ex2 (n : nat) (h : f (n+1) = 0) : 2 * f n = 0 :=
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begin
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fail_if_success {exact h},
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simp only [f] at h,
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exact h
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end
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