16 lines
419 B
Text
16 lines
419 B
Text
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import data.list
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open list
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definition append {A : Type} : list A → list A → list A,
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append nil l := l,
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append (h :: t) l := h :: (append t l)
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theorem append_nil {A : Type} (l : list A) : append nil l = l :=
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rfl
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theorem append_cons {A : Type} (h : A) (t l : list A) : append (h :: t) l = h :: (append t l) :=
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rfl
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example : append (1 :: 2 :: nil) (3 :: 4 :: 5 :: nil) = (1 :: 2 :: 3 :: 4 :: 5 :: nil) :=
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rfl
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