15 lines
426 B
Text
15 lines
426 B
Text
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import data.fin
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open fin nat
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definition nz_cases_on {C : Π n, fin (succ n) → Type}
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(H₁ : Π n, C n (fz n))
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(H₂ : Π n (f : fin n), C n (fs f))
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{n : nat}
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(f : fin (succ n)) : C n f :=
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begin
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reverts (n, f),
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show ∀ (n : nat) (f : fin (succ n)), C n f
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| m (fz m) := by apply H₁
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| m (fs f') := by apply H₂
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end
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