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import Mathlib
import OAI.RepresentationTheory.Saxl.Main
import OAI.RepresentationTheory.UniversalSquare.Balance.BalanceLeaves
import OAI.RepresentationTheory.UniversalSquare.Balance.BalanceLift
namespace OAI
/-! Balance Packing. -/
section
noncomputable section
open scoped TensorProduct
namespace Saxl.Balance
structure Packing {n d e : ℕ} (v : WordSpace n d)
(A : Fin (d*d) → Prop) (label : Fin (d*d) → ℕ) (w : WordSpace n e) where
G : Type
[groupG : Group G]
[finiteG : Finite G]
Y : Type
[addY : AddCommGroup Y]
[moduleY : Module ℂ Y]
[finiteY : FiniteDimensional ℂ Y]
c : Fin n → ℕ
σ : ℕ → ℤ
φ : G →* fiberGroup c
τ : Representation ℂ G Y
piece : Piece v c A label σ φ τ
support : SupportLE (cyclic (wordRep n e) w).toRepresentation
(Representation.coind ((fiberGroup c).subtype.comp φ) τ)
attribute [instance] Packing.groupG Packing.finiteG Packing.addY Packing.moduleY Packing.finiteY
def Packing.join {n a b d E : ℕ} {v : WordSpace a d} {u : WordSpace b d}
{A : Fin (d*d) → Prop} {label : Fin (d*d) → ℕ}
{w : WordSpace a E} {z : WordSpace b E}
(P : Packing v A label w) (Q : Packing u A label z)
(e : Fin n ≃ Fin a ⊕ Fin b) (hd : ∀ i j, P.c i ≠ Q.c j) :
Packing (positionProduct e v u) A label (positionProduct e w z) := by
letI : AddCommGroup (P.Y ⊗[ℂ] Q.Y) := Module.addCommMonoidToAddCommGroup ℂ
exact {
G := P.G × Q.G
Y := P.Y ⊗[ℂ] Q.Y
c := joinedLabels e P.c Q.c
σ := P.σ + Q.σ
φ := (joinedFiberHom e P.c Q.c).comp (P.φ.prodMap Q.φ)
τ := outer P.τ Q.τ
piece := P.piece.join Q.piece e hd
support := product_supportLE_coind
((fiberGroup P.c).subtype.comp P.φ) ((fiberGroup Q.c).subtype.comp Q.φ)
P.τ Q.τ e w z P.support Q.support }
def Packing.map {n d e E : ℕ} {v : WordSpace n d}
{A : Fin (d*d) → Prop} {label : Fin (d*d) → ℕ} {w : WordSpace n e}
(P : Packing v A label w)
(T : Representation.IntertwiningMap (wordRep n e) (wordRep n E)) :
Packing v A label (T w) :=
{ P with support := P.support.cyclic_image w T }
def Packing.lift {n d D e : ℕ} {v : WordSpace n d} {w : WordSpace n e}
(f : Fin d → Fin D) (hf : ∀ a, (f a).val = a.val)
(A : Fin (D*D) → Prop) (label : Fin (D*D) → ℕ)
(P : Packing v (A ∘ pairLetterMap f f) (label ∘ pairLetterMap f f) w) :
Packing (letterLift f v) A label w :=
{ P with piece := P.piece.lift f hf A label }
def Packing.replace {n d e E : ℕ} {v : WordSpace n d}
{A : Fin (d*d) → Prop} {label : Fin (d*d) → ℕ}
{w : WordSpace n e} (P : Packing v A label w) (z : WordSpace n E)
(h : SupportLE (cyclic (wordRep n E) z).toRepresentation
(cyclic (wordRep n e) w).toRepresentation) : Packing v A label z :=
{ P with support := h.trans P.support }
def boundedPacking {n e : ℕ} {μ : YoungDiagram} (t : Tableau n μ)
(k : ℕ) (I : Set ℕ)
(A : Fin (μ.colLen 0 * μ.colLen 0) → Prop)
(label : Fin (μ.colLen 0 * μ.colLen 0) → ℕ)
(h : ∀ a, (A a ∧ label a = k) ↔ output a ∈ I)
(hs : SupportLE (wordRep n e)
(projectedSpechtTensor t t (inOutputs I) (inOutputs_invariant I)).toRepresentation)
(w : WordSpace n e) : Packing (polytabloid t) A label w := by
let W := projectedSpechtTensor t t (inOutputs I) (inOutputs_invariant I)
let φ := (fiberGroup (fun _ : Fin n => k)).subtype.comp (singleFiberHom n k)
have hi : Function.Injective (coindLift (ρ := W.toRepresentation) φ (Representation.IntertwiningMap.id W.toRepresentation)) := by
intro x y hxy
have he := congrArg (fun z : Representation.coindV φ W.toRepresentation => z.val 1) hxy
change W.toRepresentation 1 x = W.toRepresentation 1 y at he
simpa only [map_one,Module.End.one_apply] using he
refine {
G := Equiv.Perm (Fin n)
Y := W.toSubmodule
c := fun _ => k
σ := columnOutputSums t (fun _ => k)
φ := singleFiberHom n k
τ := W.toRepresentation
piece := projectedPiece t k I A label h
support := ?_ }
exact ((SupportLE.of_injective (subrepInclusion (cyclic (wordRep n e) w))
Subtype.val_injective).trans hs).trans (SupportLE.of_injective _ hi)
theorem Packing.kronecker_pos {n : ℕ} {lam μ θ : YoungDiagram}
(a : Tableau n lam) (t : Tableau n μ)
{A : Fin (lam.colLen 0 * lam.colLen 0) → Prop}
{label : Fin (lam.colLen 0 * lam.colLen 0) → ℕ}
(w : Fin n → Fin (θ.colLen 0))
(P : Packing (polytabloid a) A label (Pi.single w 1))
(ho : ∀ x y, A x → A y → label x < label y → output x < output y)
(hc : μ.card = θ.card) (hd : Dominates μ θ)
(e : Equiv.Perm (Fin (θ.colLen 0)))
(hw : ∀ j, (Finset.univ.filter (fun i => w i = e j)).card = θ.rowLen j) :
0 < kronecker a a t :=
P.piece.kronecker_pos a t ho θ hc hd w e hw P.support
end Saxl.Balance
end
end
end OAI