Further lemmas about List.take, List.drop, List.zip and List.zipWith.

These are in a separate file from most of the list lemmas as they required importing more lemmas about natural numbers, and use omega.

take

@[simp]

theorem List.length_take {α : Type u_1} (i : Nat) (l : List α) : (List.take i l).length = min i l.length

theorem List.length_take_le {α : Type u_1} (n : Nat) (l : List α) : (List.take n l).length ≤ n

theorem List.length_take_le' {α : Type u_1} (n : Nat) (l : List α) : (List.take n l).length ≤ l.length

theorem List.length_take_of_le {n : Nat} : ∀ {α : Type u_1} {l : List α}, n ≤ l.length → (List.take n l).length = n

theorem List.take_take {α : Type u_1} (n : Nat) (m : Nat) (l : List α) : List.take n (List.take m l) = List.take (min n m) l

@[simp]

theorem List.take_replicate {α : Type u_1} (a : α) (n : Nat) (m : Nat) : List.take n (List.replicate m a) = List.replicate (min n m) a

@[simp]

theorem List.drop_replicate {α : Type u_1} (a : α) (n : Nat) (m : Nat) : List.drop n (List.replicate m a) = List.replicate (m - n) a

theorem List.take_append_eq_append_take {α : Type u_1} {l₁ : List α} {l₂ : List α} {n : Nat} : List.take n (l₁ ++ l₂) = List.take n l₁ ++ List.take (n - l₁.length) l₂

Taking the first n elements in l₁ ++ l₂ is the same as appending the first n elements of l₁ to the first n - l₁.length elements of l₂.

theorem List.take_append_of_le_length {α : Type u_1} {l₁ : List α} {l₂ : List α} {n : Nat} (h : n ≤ l₁.length) : List.take n (l₁ ++ l₂) = List.take n l₁

theorem List.take_append {α : Type u_1} {l₁ : List α} {l₂ : List α} (i : Nat) : List.take (l₁.length + i) (l₁ ++ l₂) = l₁ ++ List.take i l₂

Taking the first l₁.length + i elements in l₁ ++ l₂ is the same as appending the first i elements of l₂ to l₁.

theorem List.getElem_take {α : Type u_1} (L : List α) {i : Nat} {j : Nat} (hi : i < L.length) (hj : i < j) : L[i] = (List.take j L)[i]

The i-th element of a list coincides with the i-th element of any of its prefixes of length > i. Version designed to rewrite from the big list to the small list.

theorem List.getElem_take' {α : Type u_1} (L : List α) {j : Nat} {i : Nat} {h : i < (List.take j L).length} : (List.take j L)[i] = L[i]

The i-th element of a list coincides with the i-th element of any of its prefixes of length > i. Version designed to rewrite from the small list to the big list.

@[deprecated List.getElem_take]

theorem List.get_take {α : Type u_1} (L : List α) {i : Nat} {j : Nat} (hi : i < L.length) (hj : i < j) : L.get ⟨i, hi⟩ = (List.take j L).get ⟨i, ⋯⟩

The i-th element of a list coincides with the i-th element of any of its prefixes of length > i. Version designed to rewrite from the big list to the small list.

@[deprecated List.getElem_take]

theorem List.get_take' {α : Type u_1} (L : List α) {j : Nat} {i : Fin (List.take j L).length} : (List.take j L).get i = L.get ⟨↑i, ⋯⟩

The i-th element of a list coincides with the i-th element of any of its prefixes of length > i. Version designed to rewrite from the small list to the big list.

theorem List.getElem?_take_eq_none {α : Type u_1} {l : List α} {n : Nat} {m : Nat} (h : n ≤ m) : (List.take n l)[m]? = none

@[deprecated List.getElem?_take_eq_none]

theorem List.get?_take_eq_none {α : Type u_1} {l : List α} {n : Nat} {m : Nat} (h : n ≤ m) : (List.take n l).get? m = none

theorem List.getElem?_take_eq_if {α : Type u_1} {l : List α} {n : Nat} {m : Nat} : (List.take n l)[m]? = if m < n then l[m]? else none

@[deprecated List.getElem?_take_eq_if]

theorem List.get?_take_eq_if {α : Type u_1} {l : List α} {n : Nat} {m : Nat} : (List.take n l).get? m = if m < n then l.get? m else none

@[simp]

theorem List.take_eq_take {α : Type u_1} {l : List α} {m : Nat} {n : Nat} : List.take m l = List.take n l ↔ min m l.length = min n l.length

theorem List.take_add {α : Type u_1} (l : List α) (m : Nat) (n : Nat) : List.take (m + n) l = List.take m l ++ List.take n (List.drop m l)

theorem List.dropLast_take {α : Type u_1} {n : Nat} {l : List α} (h : n < l.length) : (List.take n l).dropLast = List.take n.pred l

theorem List.map_eq_append_split {α : Type u_1} {β : Type u_2} {f : α → β} {l : List α} {s₁ : List β} {s₂ : List β} (h : List.map f l = s₁ ++ s₂) : ∃ (l₁ : List α), ∃ (l₂ : List α), l = l₁ ++ l₂ ∧ List.map f l₁ = s₁ ∧ List.map f l₂ = s₂

drop

theorem List.drop_length_cons {α : Type u_1} {l : List α} (h : l ≠ []) (a : α) : List.drop l.length (a :: l) = [l.getLast h]

theorem List.drop_append_eq_append_drop {α : Type u_1} {l₁ : List α} {l₂ : List α} {n : Nat} : List.drop n (l₁ ++ l₂) = List.drop n l₁ ++ List.drop (n - l₁.length) l₂

Dropping the elements up to n in l₁ ++ l₂ is the same as dropping the elements up to n in l₁, dropping the elements up to n - l₁.length in l₂, and appending them.

theorem List.drop_append_of_le_length {α : Type u_1} {l₁ : List α} {l₂ : List α} {n : Nat} (h : n ≤ l₁.length) : List.drop n (l₁ ++ l₂) = List.drop n l₁ ++ l₂

@[simp]

theorem List.drop_append {α : Type u_1} {l₁ : List α} {l₂ : List α} (i : Nat) : List.drop (l₁.length + i) (l₁ ++ l₂) = List.drop i l₂

Dropping the elements up to l₁.length + i in l₁ + l₂ is the same as dropping the elements up to i in l₂.

theorem List.lt_length_drop {α : Type u_1} (L : List α) {i : Nat} {j : Nat} (h : i + j < L.length) : j < (List.drop i L).length

theorem List.getElem_drop {α : Type u_1} (L : List α) {i : Nat} {j : Nat} (h : i + j < L.length) : L[i + j] = (List.drop i L)[j]

The i + j-th element of a list coincides with the j-th element of the list obtained by dropping the first i elements. Version designed to rewrite from the big list to the small list.

@[deprecated List.getElem_drop]

theorem List.get_drop {α : Type u_1} (L : List α) {i : Nat} {j : Nat} (h : i + j < L.length) : L.get ⟨i + j, h⟩ = (List.drop i L).get ⟨j, ⋯⟩

The i + j-th element of a list coincides with the j-th element of the list obtained by dropping the first i elements. Version designed to rewrite from the big list to the small list.

theorem List.getElem_drop' {α : Type u_1} (L : List α) {i : Nat} {j : Nat} {h : j < (List.drop i L).length} : (List.drop i L)[j] = L[i + j]

The i + j-th element of a list coincides with the j-th element of the list obtained by dropping the first i elements. Version designed to rewrite from the small list to the big list.

@[deprecated List.getElem_drop']

theorem List.get_drop' {α : Type u_1} (L : List α) {i : Nat} {j : Fin (List.drop i L).length} : (List.drop i L).get j = L.get ⟨i + ↑j, ⋯⟩

The i + j-th element of a list coincides with the j-th element of the list obtained by dropping the first i elements. Version designed to rewrite from the small list to the big list.

@[simp]

theorem List.getElem?_drop {α : Type u_1} (L : List α) (i : Nat) (j : Nat) : (List.drop i L)[j]? = L[i + j]?

@[deprecated List.getElem?_drop]

theorem List.get?_drop {α : Type u_1} (L : List α) (i : Nat) (j : Nat) : (List.drop i L).get? j = L.get? (i + j)

theorem List.set_eq_take_append_cons_drop {α : Type u_1} {l : List α} {n : Nat} {a : α} : l.set n a = if n < l.length then List.take n l ++ a :: List.drop (n + 1) l else l

theorem List.drop_take {α : Type u_1} (m : Nat) (n : Nat) (l : List α) : List.drop n (List.take m l) = List.take (m - n) (List.drop n l)

theorem List.take_reverse {α : Type u_1} {xs : List α} (n : Nat) (h : n ≤ xs.length) : List.take n xs.reverse = (List.drop (xs.length - n) xs).reverse

@[reducible, inline, deprecated]

abbrev List.reverse_take {α : Type u_1} {xs : List α} (n : Nat) (h : n ≤ xs.length) : List.take n xs.reverse = (List.drop (xs.length - n) xs).reverse

Equations

• @List.reverse_take = @List.take_reverse

rotateLeft

@[simp]

theorem List.rotateLeft_replicate {α : Type u_1} {m : Nat} (n : Nat) (a : α) : (List.replicate m a).rotateLeft n = List.replicate m a

rotateRight

@[simp]

theorem List.rotateRight_replicate {α : Type u_1} {m : Nat} (n : Nat) (a : α) : (List.replicate m a).rotateRight n = List.replicate m a

zipWith

@[simp]

theorem List.length_zipWith {α : Type u_1} {β : Type u_2} {γ : Type u_3} (f : α → β → γ) (l₁ : List α) (l₂ : List β) : (List.zipWith f l₁ l₂).length = min l₁.length l₂.length

theorem List.zipWith_eq_zipWith_take_min {α : Type u_1} {β : Type u_2} : ∀ {α_1 : Type u_3} {f : α → β → α_1} (l₁ : List α) (l₂ : List β), List.zipWith f l₁ l₂ = List.zipWith f (List.take (min l₁.length l₂.length) l₁) (List.take (min l₁.length l₂.length) l₂)

@[simp]

theorem List.zipWith_replicate {α : Type u_1} {β : Type u_2} : ∀ {α_1 : Type u_3} {f : α → β → α_1} {a : α} {b : β} {m n : Nat}, List.zipWith f (List.replicate m a) (List.replicate n b) = List.replicate (min m n) (f a b)

zip

@[simp]

theorem List.length_zip {α : Type u_1} {β : Type u_2} (l₁ : List α) (l₂ : List β) : (l₁.zip l₂).length = min l₁.length l₂.length

theorem List.zip_eq_zip_take_min {α : Type u_1} {β : Type u_2} (l₁ : List α) (l₂ : List β) : l₁.zip l₂ = (List.take (min l₁.length l₂.length) l₁).zip (List.take (min l₁.length l₂.length) l₂)

@[simp]

theorem List.zip_replicate {α : Type u_1} {β : Type u_2} {a : α} {b : β} {m : Nat} {n : Nat} : (List.replicate m a).zip (List.replicate n b) = List.replicate (min m n) (a, b)

minimum?

maximum?

theorem List.maximum?_eq_some_iff' {a : Nat} {xs : List Nat} : xs.maximum? = some a ↔ a ∈ xs ∧ ∀ (b : Nat), b ∈ xs → b ≤ a