mathlib-initiative/mathlib-tactics huggingface dataset:
Module: Mathlib.Data.List.Shortlex

Goal state before:
pp: case intro.intro.inr
α : Type u_1
r : α → α → Prop
a xa : α
h✝¹ : ∀ (y : α), r y xa → Acc r y
iha :
  ∀ (y : α),
    r y xa →
      ∀ {b : List α},
        Acc (Shortlex r) b →
          (∀ (s : List α), s.length < (y :: b).length → Acc (Shortlex r) s) → Acc (Shortlex r) (y :: b)
b xb : List α
h✝ : ∀ (y : List α), Shortlex r y xb → Acc (Shortlex r) y
ihb :
  ∀ (y : List α),
    Shortlex r y xb → (∀ (s : List α), s.length < (xa :: y).length → Acc (Shortlex r) s) → Acc (Shortlex r) (xa :: y)
ih : ∀ (s : List α), s.length < (xa :: xb).length → Acc (Shortlex r) s
p : List α
lt : Shortlex r p (xa :: xb)
h2len : p.length = (xa :: xb).length
h2lex : Lex r p (xa :: xb)
⊢ Acc (Shortlex r) p

Tactic:
·

Goal state after:
case intro.intro.inr
α : Type u_1
r : α → α → Prop
a xa : α
h✝¹ : ∀ (y : α), r y xa → Acc r y
iha :
  ∀ (y : α),
    r y xa →
      ∀ {b : List α},
        Acc (Shortlex r) b →
          (∀ (s : List α), s.length < (y :: b).length → Acc (Shortlex r) s) → Acc (Shortlex r) (y :: b)
b xb : List α
h✝ : ∀ (y : List α), Shortlex r y xb → Acc (Shortlex r) y
ihb :
  ∀ (y : List α),
    Shortlex r y xb → (∀ (s : List α), s.length < (xa :: y).length → Acc (Shortlex r) s) → Acc (Shortlex r) (xa :: y)
ih : ∀ (s : List α), s.length < (xa :: xb).length → Acc (Shortlex r) s
p : List α
lt : Shortlex r p (xa :: xb)
h2len : p.length = (xa :: xb).length
h2lex : Lex r p (xa :: xb)
⊢ Acc (Shortlex r) p
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: case succ
α : Type u_1
head : ℕ
tail : List ℕ
tail_ih : ∀ (l : List α) {i : ℕ} {hi : i < (tail.splitLengths l).length}, (tail.splitLengths l)[i].length ≤ tail[i]
l : List α
n✝ : ℕ
hi : n✝ + 1 < ((head :: tail).splitLengths l).length
⊢ (take head l :: tail.splitLengths (drop head l))[n✝ + 1].length ≤ (head :: tail)[n✝ + 1]

Tactic:
·

Goal state after:
case succ
α : Type u_1
head : ℕ
tail : List ℕ
tail_ih : ∀ (l : List α) {i : ℕ} {hi : i < (tail.splitLengths l).length}, (tail.splitLengths l)[i].length ≤ tail[i]
l : List α
n✝ : ℕ
hi : n✝ + 1 < ((head :: tail).splitLengths l).length
⊢ (take head l :: tail.splitLengths (drop head l))[n✝ + 1].length ≤ (head :: tail)[n✝ + 1]
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: case nil
α : Type u_1
l : List α
h : l.length ≤ [].sum
⊢ ([].splitLengths l).flatten = l

pp: case cons
α : Type u_1
head✝ : ℕ
tail✝ : List ℕ
tail_ih✝ : ∀ (l : List α), l.length ≤ tail✝.sum → (tail✝.splitLengths l).flatten = l
l : List α
h : l.length ≤ (head✝ :: tail✝).sum
⊢ ((head✝ :: tail✝).splitLengths l).flatten = l

Tactic:
·

Goal state after:
case nil
α : Type u_1
l : List α
h : l.length ≤ [].sum
⊢ ([].splitLengths l).flatten = l
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: case nil
α : Type u_1
l : List α
h : [].sum ≤ l.length
⊢ map length ([].splitLengths l) = []

pp: case cons
α : Type u_1
head✝ : ℕ
tail✝ : List ℕ
tail_ih✝ : ∀ (l : List α), tail✝.sum ≤ l.length → map length (tail✝.splitLengths l) = tail✝
l : List α
h : (head✝ :: tail✝).sum ≤ l.length
⊢ map length ((head✝ :: tail✝).splitLengths l) = head✝ :: tail✝

Tactic:
·

Goal state after:
case nil
α : Type u_1
l : List α
h : [].sum ≤ l.length
⊢ map length ([].splitLengths l) = []
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: α : Type u_1
head : ℕ
tail : List ℕ
ih : ∀ (l : List α), tail.sum ≤ l.length → map length (tail.splitLengths l) = tail
l : List α
h : head + tail.sum ≤ l.length
⊢ head ≤ l.length ∧ tail = tail

pp: case h
α : Type u_1
head : ℕ
tail : List ℕ
ih : ∀ (l : List α), tail.sum ≤ l.length → map length (tail.splitLengths l) = tail
l : List α
h : head + tail.sum ≤ l.length
⊢ tail.sum ≤ (drop head l).length

Tactic:
·

Goal state after:
α : Type u_1
head : ℕ
tail : List ℕ
ih : ∀ (l : List α), tail.sum ≤ l.length → map length (tail.splitLengths l) = tail
l : List α
h : head + tail.sum ≤ l.length
⊢ head ≤ l.length ∧ tail = tail
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: case h
α : Type u_1
head : ℕ
tail : List ℕ
ih : ∀ (l : List α), tail.sum ≤ l.length → map length (tail.splitLengths l) = tail
l : List α
h : head + tail.sum ≤ l.length
⊢ tail.sum ≤ (drop head l).length

Tactic:
·

Goal state after:
case h
α : Type u_1
head : ℕ
tail : List ℕ
ih : ∀ (l : List α), tail.sum ≤ l.length → map length (tail.splitLengths l) = tail
l : List α
h : head + tail.sum ≤ l.length
⊢ tail.sum ≤ (drop head l).length
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: α : Type u_1
l : List α
sz : List ℕ
h : sz.sum ≤ l.length
⊢ map length (sz.splitLengths l) = sz

Tactic:
by
  induction sz generalizing l
  · simp
  case cons head tail ih =>
    simp only [sum_cons] at h
    simp only [splitLengths_cons, map_cons, length_take, cons.injEq, min_eq_left_iff]
    rw [ih]
    · simp [Nat.le_of_add_right_le h]
    · simp [Nat.le_sub_of_add_le' h]

Goal state after:
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: α : Type u_2
l : List α
sz : List ℕ
h : sz.sum ≤ l.length
i : ℕ
hi : i < (sz.splitLengths l).length
this : map length (sz.splitLengths l) = sz
⊢ (map length (sz.splitLengths l))[i] = sz[i]

pp: α : Type u_2
l : List α
sz : List ℕ
h : sz.sum ≤ l.length
i : ℕ
hi : i < (sz.splitLengths l).length
this : map length (sz.splitLengths l) = sz
⊢ i < (map length (sz.splitLengths l)).length

Tactic:
·

Goal state after:
α : Type u_2
l : List α
sz : List ℕ
h : sz.sum ≤ l.length
i : ℕ
hi : i < (sz.splitLengths l).length
this : map length (sz.splitLengths l) = sz
⊢ (map length (sz.splitLengths l))[i] = sz[i]
Module: Mathlib.Data.List.SplitLengths

Goal state before:
pp: α : Type u_2
l : List α
sz : List ℕ
h : sz.sum ≤ l.length
i : ℕ
hi : i < (sz.splitLengths l).length
this : map length (sz.splitLengths l) = sz
⊢ i < (map length (sz.splitLengths l)).length

Tactic:
·

Goal state after:
α : Type u_2
l : List α
sz : List ℕ
h : sz.sum ≤ l.length
i : ℕ
hi : i < (sz.splitLengths l).length
this : map length (sz.splitLengths l) = sz
⊢ i < (map length (sz.splitLengths l)).length
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_1
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH : ∀ {a : α} {g : List α}, ¬[] ∈ splitBy.loop r l a g []
a : α
g : List α
x✝ : Bool
heq✝ : r a b = true
⊢ ¬[] ∈ splitBy.loop r l b (a :: g) []

pp: case h_2
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH : ∀ {a : α} {g : List α}, ¬[] ∈ splitBy.loop r l a g []
a : α
g : List α
x✝ : Bool
heq✝ : r a b = false
⊢ ¬[] ∈ splitBy.loop r l b [] [(a :: g).reverse]

Tactic:
·

Goal state after:
case h_1
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH : ∀ {a : α} {g : List α}, ¬[] ∈ splitBy.loop r l a g []
a : α
g : List α
x✝ : Bool
heq✝ : r a b = true
⊢ ¬[] ∈ splitBy.loop r l b (a :: g) []
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_2
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH : ∀ {a : α} {g : List α}, ¬[] ∈ splitBy.loop r l a g []
a : α
g : List α
x✝ : Bool
heq✝ : r a b = false
⊢ ¬[] ∈ splitBy.loop r l b [] [(a :: g).reverse]

Tactic:
·

Goal state after:
case h_2
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH : ∀ {a : α} {g : List α}, ¬[] ∈ splitBy.loop r l a g []
a : α
g : List α
x✝ : Bool
heq✝ : r a b = false
⊢ ¬[] ∈ splitBy.loop r l b [] [(a :: g).reverse]
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case mp
α : Type u_1
p : ℕ
w : List α
⊢ w.HasPeriod p → ∀ i < w.length - p, w[i]? = w[i + p]?

pp: case mpr
α : Type u_1
p : ℕ
w : List α
⊢ (∀ i < w.length - p, w[i]? = w[i + p]?) → w.HasPeriod p

Tactic:
·

Goal state after:
case mp
α : Type u_1
p : ℕ
w : List α
⊢ w.HasPeriod p → ∀ i < w.length - p, w[i]? = w[i + p]?
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case nil.inl
α : Type u_1
m : List α
r : α → α → Bool
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
hm : m ∈ []
⊢ IsChain (fun x y ↦ r x y = true) m

pp: case nil.inr
α : Type u_1
r : α → α → Bool
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
⊢ IsChain (fun x y ↦ r x y = true) (a :: g).reverse

Tactic:
·

Goal state after:
case nil.inl
α : Type u_1
m : List α
r : α → α → Bool
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
hm : m ∈ []
⊢ IsChain (fun x y ↦ r x y = true) m
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case mpr
α : Type u_1
p : ℕ
w : List α
⊢ (∀ i < w.length - p, w[i]? = w[i + p]?) → w.HasPeriod p

Tactic:
·

Goal state after:
case mpr
α : Type u_1
p : ℕ
w : List α
⊢ (∀ i < w.length - p, w[i]? = w[i + p]?) → w.HasPeriod p
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case nil.inr
α : Type u_1
r : α → α → Bool
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
⊢ IsChain (fun x y ↦ r x y = true) (a :: g).reverse

Tactic:
·

Goal state after:
case nil.inr
α : Type u_1
r : α → α → Bool
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
⊢ IsChain (fun x y ↦ r x y = true) (a :: g).reverse
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case pos
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : p = 0
⊢ w[i % p]? = w[i]?

pp: case neg
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : ¬p = 0
⊢ w[i % p]? = w[i]?

Tactic:
·

Goal state after:
case pos
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : p = 0
⊢ w[i % p]? = w[i]?
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_1
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = true
h : m ∈ splitBy.loop r l b (a :: g) []
⊢ IsChain (fun x y ↦ r x y = true) m

pp: case h_2
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
h : m ∈ splitBy.loop r l b [] [g.reverse ++ [a]]
⊢ IsChain (fun x y ↦ r x y = true) m

Tactic:
·

Goal state after:
case h_1
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = true
h : m ∈ splitBy.loop r l b (a :: g) []
⊢ IsChain (fun x y ↦ r x y = true) m
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case neg
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : ¬p = 0
⊢ w[i % p]? = w[i]?

Tactic:
·

Goal state after:
case neg
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : ¬p = 0
⊢ w[i % p]? = w[i]?
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case neg.inr
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : ¬p = 0
large : p ≤ i
⊢ w[i % p]? = w[i]?

Tactic:
have len' : i - p < w.length := by lia

Goal state after:
case neg.inr
α : Type u_1
p i : ℕ
w : List α
per : w.HasPeriod p
less : i < w.length
p_zero : ¬p = 0
large : p ≤ i
len' : i - p < w.length
⊢ w[i % p]? = w[i]?
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_2
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
h : m ∈ splitBy.loop r l b [] [g.reverse ++ [a]]
⊢ IsChain (fun x y ↦ r x y = true) m

Tactic:
·

Goal state after:
case h_2
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
h : m ∈ splitBy.loop r l b [] [g.reverse ++ [a]]
⊢ IsChain (fun x y ↦ r x y = true) m
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case mp
α : Type u_1
p : ℕ
w : List α
⊢ w.HasPeriod p → ∀ i < w.length, w[i]? = w[i % p]?

pp: case mpr
α : Type u_1
p : ℕ
w : List α
⊢ (∀ i < w.length, w[i]? = w[i % p]?) → w.HasPeriod p

Tactic:
·

Goal state after:
case mp
α : Type u_1
p : ℕ
w : List α
⊢ w.HasPeriod p → ∀ i < w.length, w[i]? = w[i % p]?
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: case mpr
α : Type u_1
p : ℕ
w : List α
⊢ (∀ i < w.length, w[i]? = w[i % p]?) → w.HasPeriod p

Tactic:
·

Goal state after:
case mpr
α : Type u_1
p : ℕ
w : List α
⊢ (∀ i < w.length, w[i]? = w[i % p]?) → w.HasPeriod p
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: α : Type u_1
p : ℕ
w : List α
mod : ∀ i < w.length, w[i]? = w[i % p]?
i : ℕ
less : i < w.length - p
⊢ i + p < w.length

Tactic:
by lia

Goal state after:
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: α : Type u_1
p : ℕ
w : List α
mod : ∀ i < w.length, w[i]? = w[i % p]?
i : ℕ
less : i < w.length - p
⊢ i < w.length

Tactic:
by lia

Goal state after:
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_2.inl
α : Type u_1
r : α → α → Bool
b : α
l : List α
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
IH :
  ∀ {a_1 : α} {g_1 : List α},
    (∀ (b : α), b ∈ g_1.head? → r b a_1 = true) →
      IsChain (fun y x ↦ r x y = true) g_1 →
        g.reverse ++ [a] ∈ splitBy.loop r l a_1 g_1 [] → IsChain (fun x y ↦ r x y = true) (g.reverse ++ [a])
⊢ IsChain (fun x y ↦ r x y = true) (g.reverse ++ [a])

pp: case h_2.inr
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
hm : m ∈ splitBy.loop r l b [] []
⊢ IsChain (fun x y ↦ r x y = true) m

Tactic:
·

Goal state after:
case h_2.inl
α : Type u_1
r : α → α → Bool
b : α
l : List α
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
IH :
  ∀ {a_1 : α} {g_1 : List α},
    (∀ (b : α), b ∈ g_1.head? → r b a_1 = true) →
      IsChain (fun y x ↦ r x y = true) g_1 →
        g.reverse ++ [a] ∈ splitBy.loop r l a_1 g_1 [] → IsChain (fun x y ↦ r x y = true) (g.reverse ++ [a])
⊢ IsChain (fun x y ↦ r x y = true) (g.reverse ++ [a])
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_2.inr
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
hm : m ∈ splitBy.loop r l b [] []
⊢ IsChain (fun x y ↦ r x y = true) m

Tactic:
·

Goal state after:
case h_2.inr
α : Type u_1
m : List α
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α},
    (∀ (b : α), b ∈ g.head? → r b a = true) →
      IsChain (fun y x ↦ r x y = true) g → m ∈ splitBy.loop r l a g [] → IsChain (fun x y ↦ r x y = true) m
a : α
g : List α
hga : ∀ (b : α), b ∈ g.head? → r b a = true
hg : IsChain (fun y x ↦ r x y = true) g
x✝ : Bool
heq✝ : r a b = false
hm : m ∈ splitBy.loop r l b [] []
⊢ IsChain (fun x y ↦ r x y = true) m
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ (v ++ w)[j + u.length + p - u.length]? = v[j + p]?

pp: α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ u.length ≤ j + u.length + p

Tactic:
·

Goal state after:
α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ (v ++ w)[j + u.length + p - u.length]? = v[j + p]?
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ v[j + u.length + p - u.length]? = v[j + p]?

pp: α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ j + u.length + p - u.length < v.length

Tactic:
·

Goal state after:
α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ v[j + u.length + p - u.length]? = v[j + p]?
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ j + u.length + p - u.length < v.length

Tactic:
·

Goal state after:
α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ j + u.length + p - u.length < v.length
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_1
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α} {gs : List (List α)},
    ¬[] ∈ gs →
      IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs →
        (∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false) →
          IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l a g gs)
a : α
g : List α
gs : List (List α)
hgs' : ¬[] ∈ gs
hgs : IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs
hga : ∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false
x✝ : Bool
heq✝ : r a b = true
⊢ IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l b (a :: g) gs)

pp: case h_2
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α} {gs : List (List α)},
    ¬[] ∈ gs →
      IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs →
        (∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false) →
          IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l a g gs)
a : α
g : List α
gs : List (List α)
hgs' : ¬[] ∈ gs
hgs : IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs
hga : ∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false
x✝ : Bool
heq✝ : r a b = false
⊢ IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l b [] ((a :: g).reverse :: gs))

Tactic:
·

Goal state after:
case h_1
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α} {gs : List (List α)},
    ¬[] ∈ gs →
      IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs →
        (∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false) →
          IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l a g gs)
a : α
g : List α
gs : List (List α)
hgs' : ¬[] ∈ gs
hgs : IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs
hga : ∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false
x✝ : Bool
heq✝ : r a b = true
⊢ IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l b (a :: g) gs)
Module: Mathlib.Data.List.PeriodicityLemma

Goal state before:
pp: α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ u.length ≤ j + u.length + p

Tactic:
·

Goal state after:
α : Type u_1
u v w : List α
p : ℕ
per : (u ++ v ++ w).HasPeriod p
j : ℕ
len : j < v.length - p
shift_position : (u ++ (v ++ w))[j + u.length]? = v[j]?
eq : j + u.length + p - u.length = j + p
⊢ u.length ≤ j + u.length + p
Module: Mathlib.Data.List.SplitBy

Goal state before:
pp: case h_2
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α} {gs : List (List α)},
    ¬[] ∈ gs →
      IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs →
        (∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false) →
          IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l a g gs)
a : α
g : List α
gs : List (List α)
hgs' : ¬[] ∈ gs
hgs : IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs
hga : ∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false
x✝ : Bool
heq✝ : r a b = false
⊢ IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l b [] ((a :: g).reverse :: gs))

Tactic:
·

Goal state after:
case h_2
α : Type u_1
r : α → α → Bool
b : α
l : List α
IH :
  ∀ {a : α} {g : List α} {gs : List (List α)},
    ¬[] ∈ gs →
      IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs →
        (∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false) →
          IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l a g gs)
a : α
g : List α
gs : List (List α)
hgs' : ¬[] ∈ gs
hgs : IsChain (fun b a ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) gs
hga : ∀ (m : List α), m ∈ gs.head? → ∃ ha hb, r (m.getLast ha) ((g.reverse ++ [a]).head hb) = false
x✝ : Bool
heq✝ : r a b = false
⊢ IsChain (fun a b ↦ ∃ ha hb, r (a.getLast ha) (b.head hb) = false) (splitBy.loop r l b [] ((a :: g).reverse :: gs))