a0772dc82d
This PR fixes a local declaration internalization in `grind` that was exposed when using `grind -revert`. This bug was affecting a `grind` proof in Mathlib.
38 lines
962 B
Text
38 lines
962 B
Text
namespace List
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/-
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This example exposed a bug in the `grind` internalizer when `grind -revert`
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is used.
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-/
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variable {α : Type} {β : α → Type}
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def keys : List (Sigma β) → List α :=
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map Sigma.fst
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@[grind =]
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theorem keys_cons {s} {l : List (Sigma β)} : (s :: l).keys = s.1 :: l.keys :=
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rfl
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variable [DecidableEq α]
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def dlookup (a : α) : List (Sigma β) → Option (β a)
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| [] => none
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| ⟨a', b⟩ :: l => if h : a' = a then some (Eq.recOn h b) else dlookup a l
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@[grind =]
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theorem dlookup_cons_eq (l) (a : α) (b : β a) : dlookup a (⟨a, b⟩ :: l) = some b :=
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dif_pos rfl
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@[grind =]
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theorem dlookup_cons_ne (l) {a} : ∀ s : Sigma β, a ≠ s.1 → dlookup a (s :: l) = dlookup a l
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| ⟨_, _⟩, h => dif_neg h.symm
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@[grind =]
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theorem dlookup_isSome {a : α} {l : List (Sigma β)} : (dlookup a l).isSome ↔ a ∈ l.keys := by
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induction l with
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| nil => sorry
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| cons s _ _ =>
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by_cases a = s.fst
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· grind
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· sorry
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