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Sync from openai/math@faee2cf485a8 (part 24)
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import Mathlib
import OAI.RepresentationTheory.Saxl.Main
import OAI.RepresentationTheory.UniversalSquare.Specht.MarkedTriangle
namespace OAI
/-! Candidate Rotation. -/
section
noncomputable section
namespace UniversalTensorSquare
open Saxl
def candidateBaseRotateCell (M b δ : ℕ) (x : (candidate M b δ).cells) :
(candidate M b δ).cells :=
⟨(x.val.1,
if x.val.2 < M-2-x.val.1 then x.val.2+2
else if x.val.2 < M-2-x.val.1+2 then x.val.2-(M-2-x.val.1)
else x.val.2), by
rcases x with ⟨⟨i,j⟩, hx⟩
have hx := mem_candidate.mp hx
dsimp only at *
apply mem_candidate.mpr
split_ifs <;> omega⟩
lemma candidateBaseRotateCell_injective (M b δ : ℕ) :
Function.Injective (candidateBaseRotateCell M b δ) := by
intro x y he
have hi0 := congrArg (fun z : (candidate M b δ).cells => z.val.1) he
have hi : x.val.1 = y.val.1 := hi0
have hj := congrArg (fun z : (candidate M b δ).cells => z.val.2) he
dsimp only [candidateBaseRotateCell] at hj
rw [hi] at hj
apply Subtype.ext
apply Prod.ext hi
split_ifs at hj <;> omega
def candidateLastSwapCell (M b δ : ℕ) (hM : 4 ≤ M)
(x : (candidate M b δ).cells) : (candidate M b δ).cells :=
⟨(x.val.1, if x.val.1 = 0 then (Equiv.swap (M-1) (M+b-1)) x.val.2 else x.val.2), by
rcases x with ⟨⟨i,j⟩, hx⟩
have hx := mem_candidate.mp hx
dsimp only at *
apply mem_candidate.mpr
simp only [Equiv.swap_apply_def]
split_ifs <;> omega⟩
lemma candidateLastSwapCell_injective (M b δ : ℕ) (hM : 4 ≤ M) :
Function.Injective (candidateLastSwapCell M b δ hM) := by
intro x y he
have hi0 := congrArg (fun z : (candidate M b δ).cells => z.val.1) he
have hi : x.val.1 = y.val.1 := hi0
have hj := congrArg (fun z : (candidate M b δ).cells => z.val.2) he
dsimp only [candidateLastSwapCell] at hj
rw [hi] at hj
apply Subtype.ext
apply Prod.ext hi
by_cases h : y.val.1 = 0
· simp only [h, ite_true] at hj
exact (Equiv.swap _ _).injective hj
· simpa only [h, ite_false] using hj
def candidateRotateRow (M b δ : ℕ) (hM : 4 ≤ M) :
Equiv.Perm (candidate M b δ).cells :=
Equiv.ofBijective (candidateLastSwapCell M b δ hM ∘ candidateBaseRotateCell M b δ)
⟨(candidateLastSwapCell_injective M b δ hM).comp (candidateBaseRotateCell_injective M b δ),
Finite.surjective_of_injective
((candidateLastSwapCell_injective M b δ hM).comp (candidateBaseRotateCell_injective M b δ))⟩
@[simp] lemma candidateRotateRow_row (M b δ : ℕ) (hM : 4 ≤ M)
(x : (candidate M b δ).cells) : (candidateRotateRow M b δ hM x).val.1 = x.val.1 := rfl
lemma candidateRotateRow_mark (M b δ : ℕ) (hM : 4 ≤ M)
(x : (candidate M b δ).cells) :
candidateMark M b (candidateRotateRow M b δ hM x).val.2 ↔
x.val.1 + x.val.2 < M-2 := by
have hx := mem_candidate.mp x.property
change candidateMark M b
(if x.val.1 = 0 then Equiv.swap (M-1) (M+b-1)
(if x.val.2 < M-2-x.val.1 then x.val.2+2
else if x.val.2 < M-2-x.val.1+2 then x.val.2-(M-2-x.val.1) else x.val.2)
else (if x.val.2 < M-2-x.val.1 then x.val.2+2
else if x.val.2 < M-2-x.val.1+2 then x.val.2-(M-2-x.val.1) else x.val.2)) ↔ _
rcases x with ⟨⟨i,j⟩, hx0⟩
dsimp only at *
simp only [candidateMark, Equiv.swap_apply_def]
split_ifs <;> omega
def candidateSwap (M b δ : ℕ) : Equiv.Perm (candidate M b δ).cells where
toFun x := ⟨x.val.swap, by
rcases x with ⟨⟨i,j⟩, hx⟩
have hx := mem_candidate.mp hx
dsimp only at *
exact mem_candidate.mpr (by dsimp; omega)⟩
invFun x := ⟨x.val.swap, by
rcases x with ⟨⟨i,j⟩, hx⟩
have hx := mem_candidate.mp hx
dsimp only at *
exact mem_candidate.mpr (by dsimp; omega)⟩
left_inv x := by apply Subtype.ext; exact Prod.swap_swap _
right_inv x := by apply Subtype.ext; exact Prod.swap_swap _
def candidateRotateCol (M b δ : ℕ) (hM : 4 ≤ M) :
Equiv.Perm (candidate M b δ).cells :=
((candidateSwap M b δ).trans (candidateRotateRow M b δ hM)).trans (candidateSwap M b δ)
@[simp] lemma candidateRotateCol_col (M b δ : ℕ) (hM : 4 ≤ M)
(x : (candidate M b δ).cells) : (candidateRotateCol M b δ hM x).val.2 = x.val.2 := rfl
lemma candidateRotateCol_mark (M b δ : ℕ) (hM : 4 ≤ M)
(x : (candidate M b δ).cells) :
candidateMark M b (candidateRotateCol M b δ hM x).val.1 ↔
x.val.1 + x.val.2 < M-2 := by
have hh := candidateRotateRow_mark M b δ hM (candidateSwap M b δ x)
change candidateMark M b (candidateRotateRow M b δ hM (candidateSwap M b δ x)).val.2 ↔ _
simpa [candidateSwap, Nat.add_comm] using hh
def candidateRotateRowPositions {n M b δ : ℕ} (hM : 4 ≤ M)
(t : Tableau n (candidate M b δ)) : columnGroup (transposeTableau t) :=
⟨(t.trans (candidateRotateRow M b δ hM)).trans t.symm, by
intro i
change (t (t.symm (candidateRotateRow M b δ hM (t i)))).val.1 = _
simp only [Equiv.apply_symm_apply]
rfl⟩
def candidateRotateColPositions {n M b δ : ℕ} (hM : 4 ≤ M)
(t : Tableau n (candidate M b δ)) : columnGroup t :=
⟨(t.trans (candidateRotateCol M b δ hM)).trans t.symm, by
intro i
change (t (t.symm (candidateRotateCol M b δ hM (t i)))).val.2 = _
simp only [Equiv.apply_symm_apply]
rfl⟩
theorem candidate_projected_ne_zero {n M b δ : ℕ} (hM : 4 ≤ M)
(t : Tableau n (candidate M b δ)) :
sameMarkProjection _ _ _ (candidateMark M b) (rowColumnWord t) ≠ 0 := by
classical
let a := rowWord (transposeTableau t) ∘ (candidateRotateRowPositions hM t : Equiv.Perm _)
let c := rowWord t ∘ (candidateRotateColPositions hM t : Equiv.Perm _)
let w := mergeWords a c
have ha i : candidateMark M b (a i).val ↔ candidateTriangle t i := by
have hh := candidateRotateRow_mark M b δ hM (t i)
simpa [a, rowWord, transposeTableau, candidateRotateRowPositions, candidateTriangle] using hh
have hc i : candidateMark M b (c i).val ↔ candidateTriangle t i := by
have hh := candidateRotateCol_mark M b δ hM (t i)
simpa [c, rowWord, candidateRotateColPositions, candidateTriangle] using hh
intro hz
have he := congrFun hz w
change sameMarkProjection _ _ _ (candidateMark M b) (rowColumnWord t) w = 0 at he
simp only [sameMarkProjection, Representation.IntertwiningMap.coe_mk, LinearMap.coe_mk,
AddHom.coe_mk, rowColumnWord, wordTensor_tmul, w, splitLeft_merge, splitRight_merge,
a, c, polytabloid_column_coeff] at he
have hn (g : Equiv.Perm (Fin n)) : signC g ≠ 0 := by
intro hz
have hh := signC_mul_self g
rw [hz, zero_mul] at hh
exact zero_ne_one hh
have hpac : ∀ i, candidateMark M b (a i).val ↔ candidateMark M b (c i).val :=
fun i => (ha i).trans (hc i).symm
rw [ite_eq_left hpac] at he
exact mul_ne_zero (hn _) (hn _) he
end UniversalTensorSquare
end
end
end OAI