39 lines
776 B
Text
39 lines
776 B
Text
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import data.list
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constant A : Type₁
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constant B : Type₁
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constant coe : A → B
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attribute coe [coercion]
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variable f : B → B
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variable a : A
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set_option pp.coercions true
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check f a
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constant C : Type₁
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variable g : (C → B) → B
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variable h : C → A
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check g h
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definition tst (g : C → B) : Prop := g = h
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open bool list
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definition bool_to_Prop [coercion] [reducible] (b : bool) : Prop := b = tt
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definition bpred_dec [instance] {A : Type} (p : A → bool) : ∀ a, decidable (p a = tt) :=
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begin
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intro a,
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eapply (bool.rec_on (p a)),
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right, contradiction,
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left, reflexivity
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end
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definition negb : bool → bool := bool.rec tt ff
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check filter negb [tt, ff, tt, ff]
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eval filter negb [tt, ff, tt, ff]
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example : filter negb [tt, ff, tt, ff] = [ff, ff] :=
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rfl
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