23 lines
517 B
Text
23 lines
517 B
Text
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open bool
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definition to_pred {A : Type} (p : A → bool) : A → Prop :=
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λ a, p a = tt
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definition to_pred_dec₁ [instance] {A : Type} (p : A → bool)
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: decidable_pred (to_pred p) :=
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begin
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intro a, unfold to_pred,
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induction p a,
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right, contradiction,
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left, reflexivity
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end
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definition to_pred_dec₂ [instance] {A : Type} (p : A → bool)
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: decidable_pred (to_pred p) :=
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begin
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intro a, unfold to_pred,
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cases p a,
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right, contradiction,
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left, reflexivity
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end
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