14 lines
377 B
Text
14 lines
377 B
Text
theorem n_minus_one_le_n {n : Nat} : n > 0 → n - 1 < n := by
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cases n with
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| zero => simp []
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| succ n =>
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intros
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rw [Nat.succ_eq_add_one, Nat.add_sub_cancel]
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apply Nat.le.refl
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partial def foo : Array Int → Int
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| arr => Id.run do
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let mut r : Int := 1
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while h : arr.size > 0 do
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r := r * arr[arr.size - 1]'(by apply n_minus_one_le_n h)
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return r
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