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import OAI.LinearAlgebra.MatrixMultiplication.CoppersmithWinograd.ComplexCoppersmithWinograd
import Mathlib.Data.Fintype.Pi
namespace OAI
/-! Coppersmith–Winograd tensors, tensor powers and local restrictions. -/
noncomputable section
namespace MatrixMultiplication.Foundation.CWOriginalWords
open scoped BigOperators
abbrev OriginalComponent :=
{xyz : Fin 3 × Fin 3 × Fin 3 // xyz.1.val + xyz.2.1.val + xyz.2.2.val = 2}
@[simp] theorem originalComponent_card : Fintype.card OriginalComponent = 6 := by
decide
namespace OriginalComponent
def x (g : OriginalComponent) : Fin 3 := g.val.1
def y (g : OriginalComponent) : Fin 3 := g.val.2.1
def z (g : OriginalComponent) : Fin 3 := g.val.2.2
theorem sum_eq_two (g : OriginalComponent) : g.x.val + g.y.val + g.z.val = 2 :=
g.property
@[ext] theorem ext {g h : OriginalComponent}
(hx : g.x = h.x) (hy : g.y = h.y) (hz : g.z = h.z) : g = h := by
apply Subtype.ext
exact Prod.ext hx (Prod.ext hy hz)
theorem eq_of_xy {g h : OriginalComponent} (hx : g.x = h.x) (hy : g.y = h.y) : g = h := by
apply ext hx hy
apply Fin.ext
have hg := g.sum_eq_two
have hh := h.sum_eq_two
rw [hx, hy] at hg
omega
theorem eq_of_xz {g h : OriginalComponent} (hx : g.x = h.x) (hz : g.z = h.z) : g = h := by
apply ext hx _ hz
apply Fin.ext
have hg := g.sum_eq_two
have hh := h.sum_eq_two
rw [hx, hz] at hg
omega
theorem eq_of_yz {g h : OriginalComponent} (hy : g.y = h.y) (hz : g.z = h.z) : g = h := by
apply ext _ hy hz
apply Fin.ext
have hg := g.sum_eq_two
have hh := h.sum_eq_two
rw [hy, hz] at hg
omega
@[simp] theorem coefficient (g : OriginalComponent) :
CoppersmithWinograd.tensor g.x g.y g.z = 1 := by
simp only [CoppersmithWinograd.tensor, g.sum_eq_two, ite_true]
def coordinate (g : OriginalComponent) : Fin 3 → Fin 3
| 0 => g.x
| 1 => g.y
| 2 => g.z
theorem coordinate_sum (g : OriginalComponent) :
(∑ side, (g.coordinate side).val) = 2 := by
simpa [coordinate, Fin.sum_univ_succ, add_assoc] using g.sum_eq_two
theorem coordinate_injective : Function.Injective coordinate := by
intro g h he
exact ext (congrFun he 0) (congrFun he 1) (congrFun he 2)
def permute (σ : Equiv.Perm (Fin 3)) (g : OriginalComponent) : OriginalComponent :=
⟨(g.coordinate (σ 0), g.coordinate (σ 1), g.coordinate (σ 2)), by
have h := (Equiv.sum_comp σ (fun side => (g.coordinate side).val)).trans g.coordinate_sum
simpa [Fin.sum_univ_succ, add_assoc] using h⟩
@[simp] theorem coordinate_permute (σ : Equiv.Perm (Fin 3))
(g : OriginalComponent) (side : Fin 3) :
(permute σ g).coordinate side = g.coordinate (σ side) := by
fin_cases side <;> rfl
theorem permute_injective (σ : Equiv.Perm (Fin 3)) : Function.Injective (permute σ) := by
intro g h he
apply coordinate_injective
funext side
have hs := congrArg (fun a : OriginalComponent => a.coordinate (σ.symm side)) he
simpa only [coordinate_permute, Equiv.apply_symm_apply] using hs
end OriginalComponent
theorem tensor_ne_zero_iff (x y z : Fin 3) :
CoppersmithWinograd.tensor x y z ≠ 0 ↔ x.val + y.val + z.val = 2 := by
by_cases h : x.val + y.val + z.val = 2 <;> simp [CoppersmithWinograd.tensor, h]
def decodeComponent (x y z : Fin 3) : OriginalComponent :=
if h : x.val + y.val + z.val = 2 then ⟨(x, y, z), h⟩
else ⟨(2, 0, 0), by decide⟩
@[simp] theorem decodeComponent_coordinates (g : OriginalComponent) :
decodeComponent g.x g.y g.z = g := by
rw [decodeComponent, dite_eq_left g.sum_eq_two]
apply Subtype.ext
rfl
section Words
variable {Site : Type*}
def xWord (word : Site → OriginalComponent) : Site → Fin 3 := fun s => (word s).x
def yWord (word : Site → OriginalComponent) : Site → Fin 3 := fun s => (word s).y
def zWord (word : Site → OriginalComponent) : Site → Fin 3 := fun s => (word s).z
def originalWords (word : Site → OriginalComponent) :
(Site → Fin 3) × (Site → Fin 3) × (Site → Fin 3) :=
(xWord word, yWord word, zWord word)
def decodeWord (x y z : Site → Fin 3) : Site → OriginalComponent :=
fun s => decodeComponent (x s) (y s) (z s)
@[simp] theorem decodeWord_originalWords (word : Site → OriginalComponent) :
decodeWord (xWord word) (yWord word) (zWord word) = word := by
funext s
exact decodeComponent_coordinates (word s)
theorem originalWords_decodeWord_of_support (x y z : Site → Fin 3)
(support : ∀ s, (x s).val + (y s).val + (z s).val = 2) :
originalWords (decodeWord x y z) = (x, y, z) := by
apply Prod.ext
· funext s
simp [originalWords, xWord, decodeWord, decodeComponent, support s,
OriginalComponent.x]
· apply Prod.ext
· funext s
simp [originalWords, yWord, decodeWord, decodeComponent, support s,
OriginalComponent.y]
· funext s
simp [originalWords, zWord, decodeWord, decodeComponent, support s,
OriginalComponent.z]
theorem decodeWord_eq_iff_of_support (x y z : Site → Fin 3)
(support : ∀ s, (x s).val + (y s).val + (z s).val = 2)
(word : Site → OriginalComponent) :
decodeWord x y z = word ↔ x = xWord word ∧ y = yWord word ∧ z = zWord word := by
constructor
· intro he
have h := originalWords_decodeWord_of_support x y z support
rw [he] at h
exact ⟨(congrArg Prod.fst h).symm,
(congrArg (fun words => words.2.1) h).symm,
(congrArg (fun words => words.2.2) h).symm⟩
· rintro ⟨rfl, rfl, rfl⟩
exact decodeWord_originalWords word
theorem originalWords_injective : Function.Injective (originalWords (Site := Site)) := by
intro first second he
funext s
apply OriginalComponent.ext
· exact congrFun (congrArg Prod.fst he) s
· exact congrFun (congrArg (fun words => words.2.1) he) s
· exact congrFun (congrArg (fun words => words.2.2) he) s
theorem xyWords_injective :
Function.Injective (fun word : Site → OriginalComponent => (xWord word, yWord word)) := by
intro first second he
funext s
exact OriginalComponent.eq_of_xy
(congrFun (congrArg Prod.fst he) s) (congrFun (congrArg Prod.snd he) s)
theorem xzWords_injective :
Function.Injective (fun word : Site → OriginalComponent => (xWord word, zWord word)) := by
intro first second he
funext s
exact OriginalComponent.eq_of_xz
(congrFun (congrArg Prod.fst he) s) (congrFun (congrArg Prod.snd he) s)
theorem yzWords_injective :
Function.Injective (fun word : Site → OriginalComponent => (yWord word, zWord word)) := by
intro first second he
funext s
exact OriginalComponent.eq_of_yz
(congrFun (congrArg Prod.fst he) s) (congrFun (congrArg Prod.snd he) s)
def permuteWord (orientation : Site → Equiv.Perm (Fin 3))
(word : Site → OriginalComponent) : Site → OriginalComponent :=
fun s => OriginalComponent.permute (orientation s) (word s)
theorem permuteWord_injective (orientation : Site → Equiv.Perm (Fin 3)) :
Function.Injective (permuteWord orientation) := by
intro first second he
funext s
exact OriginalComponent.permute_injective (orientation s) (congrFun he s)
theorem oriented_originalWords_injective (orientation : Site → Equiv.Perm (Fin 3)) :
Function.Injective (fun word => originalWords (permuteWord orientation word)) :=
originalWords_injective.comp (permuteWord_injective orientation)
variable [Fintype Site]
def siteTensor : Tensor ℂ (Site → Fin 3) (Site → Fin 3) (Site → Fin 3) :=
fun x y z => ∏ s, CoppersmithWinograd.tensor (x s) (y s) (z s)
@[simp] theorem siteTensor_originalWords (word : Site → OriginalComponent) :
siteTensor (xWord word) (yWord word) (zWord word) = 1 := by
simp only [siteTensor, xWord, yWord, zWord, OriginalComponent.coefficient,
Finset.prod_const_one]
theorem siteTensor_originalWords_ne_zero (word : Site → OriginalComponent) :
siteTensor (xWord word) (yWord word) (zWord word) ≠ 0 := by
rw [siteTensor_originalWords]
exact one_ne_zero
theorem siteTensor_oriented_originalWords (orientation : Site → Equiv.Perm (Fin 3))
(word : Site → OriginalComponent) :
siteTensor (xWord (permuteWord orientation word))
(yWord (permuteWord orientation word)) (zWord (permuteWord orientation word)) = 1 :=
siteTensor_originalWords _
theorem siteTensor_ne_zero_iff (x y z : Site → Fin 3) :
siteTensor x y z ≠ 0 ↔ ∀ s, (x s).val + (y s).val + (z s).val = 2 := by
simp only [siteTensor, Finset.prod_ne_zero_iff, Finset.mem_univ, forall_const,
tensor_ne_zero_iff]
def supportedWordEquiv : (Site → OriginalComponent) ≃
{words : (Site → Fin 3) × (Site → Fin 3) × (Site → Fin 3) //
siteTensor words.1 words.2.1 words.2.2 ≠ 0} where
toFun word := ⟨originalWords word, siteTensor_originalWords_ne_zero word⟩
invFun words s := ⟨(words.val.1 s, words.val.2.1 s, words.val.2.2 s),
(siteTensor_ne_zero_iff _ _ _).mp words.property s⟩
left_inv word := by
funext s
apply Subtype.ext
rfl
right_inv words := by
apply Subtype.ext
rfl
section WordCard
local instance : DecidableEq Site := Classical.decEq Site
@[simp] theorem word_card : Fintype.card (Site → OriginalComponent) =
6 ^ Fintype.card Site := by
simp only [Fintype.card_pi, originalComponent_card, Finset.prod_const, Finset.card_univ]
end WordCard
theorem siteTensor_eq_power {n : ℕ} (site : Fin n ≃ Site)
(x y z : Site → Fin 3) :
siteTensor x y z = Tensor.power CoppersmithWinograd.tensor n
(fun i => x (site i)) (fun i => y (site i)) (fun i => z (site i)) := by
exact (site.prod_comp (fun s => CoppersmithWinograd.tensor (x s) (y s) (z s))).symm
end Words
@[simp] theorem power_originalWords (n : ℕ) (word : Fin n → OriginalComponent) :
Tensor.power CoppersmithWinograd.tensor n (xWord word) (yWord word) (zWord word) = 1 :=
siteTensor_originalWords word
theorem power_originalWords_ne_zero (n : ℕ) (word : Fin n → OriginalComponent) :
Tensor.power CoppersmithWinograd.tensor n (xWord word) (yWord word) (zWord word) ≠ 0 :=
siteTensor_originalWords_ne_zero word
end MatrixMultiplication.Foundation.CWOriginalWords
end
end OAI