12 lines
252 B
Text
12 lines
252 B
Text
open nat
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def nat.ind_on {p : nat → Prop} (n : nat) (h₁ : p 0) (h₂ : ∀ n, p n → p (succ n)) : p n :=
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nat.rec_on n h₁ h₂
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example : ∀ a b : nat, a + b = b + a :=
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begin
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intro a,
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apply nat.ind_on a,
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trace_state,
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repeat {admit}
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end
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