Lemmas about List.range and List.enum

Ranges and enumeration

range'

@[simp]

theorem List.mem_range'_1 {s n m : Nat} : m ∈ range' s n ↔ s ≤ m ∧ m < s + n

theorem List.getLast?_range' {s : Nat} (n : Nat) : (range' s n).getLast? = if n = 0 then none else some (s + n - 1)

@[simp]

theorem List.getLast_range' {s : Nat} (n : Nat) (h : range' s n ≠ []) : (range' s n).getLast h = s + n - 1

theorem List.pairwise_lt_range' (s n : Nat) (step : Nat := 1) (pos : 0 < step := by simp) : Pairwise (fun (x1 x2 : Nat) => x1 < x2) (range' s n step)

theorem List.pairwise_le_range' (s n : Nat) (step : Nat := 1) : Pairwise (fun (x1 x2 : Nat) => x1 ≤ x2) (range' s n step)

theorem List.nodup_range' (s n : Nat) (step : Nat := 1) (h : 0 < step := by simp) : (range' s n step).Nodup

theorem List.map_sub_range' {step : Nat} (a s n : Nat) (h : a ≤ s) : map (fun (x : Nat) => x - a) (range' s n step) = range' (s - a) n step

@[simp]

theorem List.range'_eq_singleton {s n a : Nat} : range' s n = [a] ↔ s = a ∧ n = 1

theorem List.range'_eq_append_iff {s n : Nat} {xs ys : List Nat} : range' s n = xs ++ ys ↔ ∃ (k : Nat), k ≤ n ∧ xs = range' s k ∧ ys = range' (s + k) (n - k)

@[simp]

theorem List.find?_range'_eq_some {s n i : Nat} {p : Nat → Bool} : find? p (range' s n) = some i ↔ p i = true ∧ i ∈ range' s n ∧ ∀ (j : Nat), s ≤ j → j < i → (!p j) = true

theorem List.find?_range'_eq_none {s n : Nat} {p : Nat → Bool} : find? p (range' s n) = none ↔ ∀ (i : Nat), s ≤ i → i < s + n → (!p i) = true

theorem List.erase_range' {s n i : Nat} : (range' s n).erase i = range' s (min n (i - s)) ++ range' (max s (i + 1)) (min s (i + 1) + n - (i + 1))

range

theorem List.reverse_range' (s n : Nat) : (range' s n).reverse = map (fun (x : Nat) => s + n - 1 - x) (range n)

@[simp]

theorem List.mem_range {m n : Nat} : m ∈ range n ↔ m < n

theorem List.not_mem_range_self {n : Nat} : ¬n ∈ range n

theorem List.self_mem_range_succ (n : Nat) : n ∈ range (n + 1)

theorem List.pairwise_lt_range (n : Nat) : Pairwise (fun (x1 x2 : Nat) => x1 < x2) (range n)

theorem List.pairwise_le_range (n : Nat) : Pairwise (fun (x1 x2 : Nat) => x1 ≤ x2) (range n)

theorem List.take_range (m n : Nat) : take m (range n) = range (min m n)

theorem List.nodup_range (n : Nat) : (range n).Nodup

@[simp]

theorem List.find?_range_eq_some {n i : Nat} {p : Nat → Bool} : find? p (range n) = some i ↔ p i = true ∧ i ∈ range n ∧ ∀ (j : Nat), j < i → (!p j) = true

theorem List.find?_range_eq_none {n : Nat} {p : Nat → Bool} : find? p (range n) = none ↔ ∀ (i : Nat), i < n → (!p i) = true

theorem List.erase_range {n i : Nat} : (range n).erase i = range (min n i) ++ range' (i + 1) (n - (i + 1))

iota

theorem List.iota_eq_reverse_range' (n : Nat) : iota n = (range' 1 n).reverse

@[simp]

theorem List.length_iota (n : Nat) : (iota n).length = n

@[simp]

theorem List.iota_eq_nil {n : Nat} : iota n = [] ↔ n = 0

theorem List.iota_ne_nil {n : Nat} : iota n ≠ [] ↔ n ≠ 0

@[simp]

theorem List.mem_iota {m n : Nat} : m ∈ iota n ↔ 0 < m ∧ m ≤ n

@[simp]

theorem List.iota_inj {n n' : Nat} : iota n = iota n' ↔ n = n'

theorem List.iota_eq_cons_iff {n a : Nat} {xs : List Nat} : iota n = a :: xs ↔ n = a ∧ 0 < n ∧ xs = iota (n - 1)

theorem List.iota_eq_append_iff {n : Nat} {xs ys : List Nat} : iota n = xs ++ ys ↔ ∃ (k : Nat), k ≤ n ∧ xs = (range' (k + 1) (n - k)).reverse ∧ ys = iota k

theorem List.pairwise_gt_iota (n : Nat) : Pairwise (fun (x1 x2 : Nat) => x1 > x2) (iota n)

theorem List.nodup_iota (n : Nat) : (iota n).Nodup

@[simp]

theorem List.head?_iota (n : Nat) : (iota n).head? = if n = 0 then none else some n

@[simp]

theorem List.head_iota (n : Nat) (h : iota n ≠ []) : (iota n).head h = n

@[simp]

theorem List.tail_iota (n : Nat) : (iota n).tail = iota (n - 1)

@[simp]

theorem List.reverse_iota {n : Nat} : (iota n).reverse = range' 1 n

@[simp]

theorem List.getLast?_iota (n : Nat) : (iota n).getLast? = if n = 0 then none else some 1

@[simp]

theorem List.getLast_iota (n : Nat) (h : iota n ≠ []) : (iota n).getLast h = 1

theorem List.find?_iota_eq_none {n : Nat} {p : Nat → Bool} : find? p (iota n) = none ↔ ∀ (i : Nat), 0 < i → i ≤ n → (!p i) = true

@[simp]

theorem List.find?_iota_eq_some {n i : Nat} {p : Nat → Bool} : find? p (iota n) = some i ↔ p i = true ∧ i ∈ iota n ∧ ∀ (j : Nat), i < j → j ≤ n → (!p j) = true

enumFrom

@[simp]

theorem List.enumFrom_singleton {α : Type u_1} (x : α) (n : Nat) : enumFrom n [x] = [(n, x)]

@[simp]

theorem List.head?_enumFrom {α : Type u_1} (n : Nat) (l : List α) : (enumFrom n l).head? = Option.map (fun (a : α) => (n, a)) l.head?

@[simp]

theorem List.getLast?_enumFrom {α : Type u_1} (n : Nat) (l : List α) : (enumFrom n l).getLast? = Option.map (fun (a : α) => (n + l.length - 1, a)) l.getLast?

theorem List.mk_add_mem_enumFrom_iff_getElem? {α : Type u_1} {n i : Nat} {x : α} {l : List α} : (n + i, x) ∈ enumFrom n l ↔ l[i]? = some x

theorem List.mk_mem_enumFrom_iff_le_and_getElem?_sub {α : Type u_1} {n i : Nat} {x : α} {l : List α} : (i, x) ∈ enumFrom n l ↔ n ≤ i ∧ l[i - n]? = some x

theorem List.le_fst_of_mem_enumFrom {α : Type u_1} {x : Nat × α} {n : Nat} {l : List α} (h : x ∈ enumFrom n l) : n ≤ x.fst

theorem List.fst_lt_add_of_mem_enumFrom {α : Type u_1} {x : Nat × α} {n : Nat} {l : List α} (h : x ∈ enumFrom n l) : x.fst < n + l.length

theorem List.map_enumFrom {α : Type u_1} {β : Type u_2} (f : α → β) (n : Nat) (l : List α) : map (Prod.map id f) (enumFrom n l) = enumFrom n (map f l)

theorem List.snd_mem_of_mem_enumFrom {α : Type u_1} {x : Nat × α} {n : Nat} {l : List α} (h : x ∈ enumFrom n l) : x.snd ∈ l

theorem List.snd_eq_of_mem_enumFrom {α : Type u_1} {x : Nat × α} {n : Nat} {l : List α} (h : x ∈ enumFrom n l) : x.snd = l[x.fst - n]

theorem List.mem_enumFrom {α : Type u_1} {x : α} {i j : Nat} {xs : List α} (h : (i, x) ∈ enumFrom j xs) : j ≤ i ∧ i < j + xs.length ∧ x = xs[i - j]

theorem List.enumFrom_map {α : Type u_1} {β : Type u_2} (n : Nat) (l : List α) (f : α → β) : enumFrom n (map f l) = map (Prod.map id f) (enumFrom n l)

theorem List.enumFrom_append {α : Type u_1} (xs ys : List α) (n : Nat) : enumFrom n (xs ++ ys) = enumFrom n xs ++ enumFrom (n + xs.length) ys

theorem List.enumFrom_eq_cons_iff {α : Type u_1} {x : Nat × α} {l' : List (Nat × α)} {l : List α} {n : Nat} : enumFrom n l = x :: l' ↔ ∃ (a : α), ∃ (as : List α), l = a :: as ∧ x = (n, a) ∧ l' = enumFrom (n + 1) as

theorem List.enumFrom_eq_append_iff {α : Type u_1} {l₁ l₂ : List (Nat × α)} {l : List α} {n : Nat} : enumFrom n l = l₁ ++ l₂ ↔ ∃ (l₁' : List α), ∃ (l₂' : List α), l = l₁' ++ l₂' ∧ l₁ = enumFrom n l₁' ∧ l₂ = enumFrom (n + l₁'.length) l₂'

enum

@[simp]

theorem List.enum_eq_nil_iff {α : Type u_1} {l : List α} : l.enum = [] ↔ l = []

@[deprecated List.enum_eq_nil_iff (since := "2024-11-04")]

theorem List.enum_eq_nil {α : Type u_1} {l : List α} : l.enum = [] ↔ l = []

@[simp]

theorem List.enum_singleton {α : Type u_1} (x : α) : [x].enum = [(0, x)]

@[simp]

theorem List.enum_length {α✝ : Type u_1} {l : List α✝} : l.enum.length = l.length

@[simp]

theorem List.getElem?_enum {α : Type u_1} (l : List α) (n : Nat) : l.enum[n]? = Option.map (fun (a : α) => (n, a)) l[n]?

@[simp]

theorem List.getElem_enum {α : Type u_1} (l : List α) (i : Nat) (h : i < l.enum.length) : l.enum[i] = (i, l[i])

@[simp]

theorem List.head?_enum {α : Type u_1} (l : List α) : l.enum.head? = Option.map (fun (a : α) => (0, a)) l.head?

@[simp]

theorem List.getLast?_enum {α : Type u_1} (l : List α) : l.enum.getLast? = Option.map (fun (a : α) => (l.length - 1, a)) l.getLast?

@[simp]

theorem List.tail_enum {α : Type u_1} (l : List α) : l.enum.tail = enumFrom 1 l.tail

theorem List.mk_mem_enum_iff_getElem? {α : Type u_1} {i : Nat} {x : α} {l : List α} : (i, x) ∈ l.enum ↔ l[i]? = some x

theorem List.mem_enum_iff_getElem? {α : Type u_1} {x : Nat × α} {l : List α} : x ∈ l.enum ↔ l[x.fst]? = some x.snd

theorem List.fst_lt_of_mem_enum {α : Type u_1} {x : Nat × α} {l : List α} (h : x ∈ l.enum) : x.fst < l.length

theorem List.snd_mem_of_mem_enum {α : Type u_1} {x : Nat × α} {l : List α} (h : x ∈ l.enum) : x.snd ∈ l

theorem List.snd_eq_of_mem_enum {α : Type u_1} {x : Nat × α} {l : List α} (h : x ∈ l.enum) : x.snd = l[x.fst]

theorem List.mem_enum {α : Type u_1} {x : α} {i : Nat} {xs : List α} (h : (i, x) ∈ xs.enum) : i < xs.length ∧ x = xs[i]

theorem List.map_enum {α : Type u_1} {β : Type u_2} (f : α → β) (l : List α) : map (Prod.map id f) l.enum = (map f l).enum

@[simp]

theorem List.enum_map_fst {α : Type u_1} (l : List α) : map Prod.fst l.enum = range l.length

@[simp]

theorem List.enum_map_snd {α : Type u_1} (l : List α) : map Prod.snd l.enum = l

theorem List.enum_map {α : Type u_1} {β : Type u_2} (l : List α) (f : α → β) : (map f l).enum = map (Prod.map id f) l.enum

theorem List.enum_append {α : Type u_1} (xs ys : List α) : (xs ++ ys).enum = xs.enum ++ enumFrom xs.length ys

theorem List.enum_eq_zip_range {α : Type u_1} (l : List α) : l.enum = (range l.length).zip l

@[simp]

theorem List.unzip_enum_eq_prod {α : Type u_1} (l : List α) : l.enum.unzip = (range l.length, l)

theorem List.enum_eq_cons_iff {α : Type u_1} {x : Nat × α} {l' : List (Nat × α)} {l : List α} : l.enum = x :: l' ↔ ∃ (a : α), ∃ (as : List α), l = a :: as ∧ x = (0, a) ∧ l' = enumFrom 1 as

theorem List.enum_eq_append_iff {α : Type u_1} {l₁ l₂ : List (Nat × α)} {l : List α} : l.enum = l₁ ++ l₂ ↔ ∃ (l₁' : List α), ∃ (l₂' : List α), l = l₁' ++ l₂' ∧ l₁ = l₁'.enum ∧ l₂ = enumFrom l₁'.length l₂'