23 lines
778 B
Text
23 lines
778 B
Text
module
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variable {α : Type u} {l : List α} {P Q : α → Bool}
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attribute [grind] List.countP_nil List.countP_cons
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theorem List.countP_le_countP (hpq : ∀ x ∈ l, P x → Q x) :
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l.countP P ≤ l.countP Q := by
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induction l <;> grind
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-- TODO: how to explain to the user that `l.countP P ≤ l.countP Q` is a bad pattern
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grind_pattern List.countP_le_countP => l.countP P, l.countP Q
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theorem List.countP_lt_countP (hpq : ∀ x ∈ l, P x → Q x) (y:α) (hx: y ∈ l) (hxP : P y = false) (hxQ : Q y) :
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l.countP P < l.countP Q := by
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induction l <;> grind
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/--
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info: List.countP_nil: [@List.countP #1 #0 (@List.nil _)]
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---
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info: List.countP_cons: [@List.countP #3 #2 (@List.cons _ #1 #0)]
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-/
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#guard_msgs (info) in
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attribute [grind?] List.countP_nil List.countP_cons
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