14 lines
359 B
Text
14 lines
359 B
Text
universe u v
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inductive Imf {α : Type u} {β : Type v} (f : α → β) : β → Type (max u v)
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| mk : (a : α) → Imf f (f a)
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def h {α β} {f : α → β} : {b : β} → Imf f b → α
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| _, Imf.mk a => a
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#print h
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infix:50 " ≅ " => HEq
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theorem ex : ∀ {α β : Sort u} (h : α = β) (a : α), cast h a ≅ a
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| α, _, rfl, a => HEq.refl a
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#print ex
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