13 lines
378 B
Text
13 lines
378 B
Text
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import data.list
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open list
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lemma last_singleton [simp] {A : Type} (a : A) : last [a] !cons_ne_nil = a :=
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rfl
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lemma last_cons_cons [simp] {A : Type} (a₁ a₂ : A) (l : list A) : last (a₁::a₂::l) !cons_ne_nil = last (a₂::l) !cons_ne_nil :=
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rfl
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theorem last_concat [simp] {A : Type} {x : A} : ∀ {l : list A}, last (concat x l) !concat_ne_nil = x :=
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by rec_inst_simp
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