16 lines
424 B
Text
16 lines
424 B
Text
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import data.nat.basic data.bool
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open bool nat
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reducible nat.rec_on
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definition is_eq (a b : nat) : bool :=
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nat.rec_on a
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(λ b, nat.cases_on b tt (λb₁, ff))
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(λ a₁ r₁ b, nat.cases_on b ff (λb₁, r₁ b₁))
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b
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example (a₁ : nat) (b : nat) : true :=
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@nat.cases_on (λ (n : nat), true) b
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true.intro
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(λ (b₁ : _),
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have aux : is_eq a₁ b₁ = is_eq (succ a₁) (succ b₁), from rfl,
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true.intro)
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