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refactor(library/data/list/perm): remove dead code

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Leonardo de Moura 2015-04-08 09:32:28 -07:00
parent ef1b057b63
commit 56d20852aa
1 changed files with 0 additions and 18 deletions
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18
library/data/list/perm.lean
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@ -257,24 +257,6 @@ by_cases
inr (λ p : l₁ ~ l₂, absurd (length_eq_length_of_perm p) neql))
end dec
theorem discriminate {P : Prop} {l : list A} : (l = [] → P) → (∀ h t, l = h::t → P) → P :=
list.cases_on l
(λ h₁ h₂, h₁ rfl)
(λ a l h₁ h₂, h₂ a l rfl)
theorem discriminate₂ {P : Prop} {l : list A} : (l = [] → P) → (∀ a, l = [a] → P) → (∀ a₁ a₂ t, l = a₁::a₂::t → P) → P :=
list.cases_on l
(λ h₁ h₂ h₃, h₁ rfl)
(λ a₁ t, list.cases_on t
(λ h₁ h₂ h₃, h₂ a₁ rfl)
(λ a₂ t₂ h₁ h₂ h₃, h₃ a₁ a₂ t₂ rfl))
theorem tail_eq {a₁ a₂ : A} {t₁ t₂ : list A} : a₁::t₁ = a₂::t₂ → t₁ = t₂ :=
assume h, list.no_confusion h (λ e₁ e₂, e₂)
theorem head_eq {a₁ a₂ : A} {t₁ t₂ : list A} : a₁::t₁ = a₂::t₂ → a₁ = a₂ :=
assume h, list.no_confusion h (λ e₁ e₂, e₁)
-- Auxiliary theorem for performing cases-analysis on l₂.
-- We use it to prove perm_inv_core.
private theorem discr {P : Prop} {a b : A} {l₁ l₂ l₃ : list A} :