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DerivedAlgGeo.CategoryTheory.Triangulated.FourierMukai.DualTwistKernel

Kernel realizations of left-adjunction dual twists #

Let Φ_Q ⊣ Φ_P, where Φ_P : X ⥤ Y is presented by a kernel for a correspondence C and Φ_Q : Y ⥤ X is its supplied kernel-presented left adjoint. The adjunction unit has the form

id_Y ⟶ Φ_Q ⋙ Φ_P.

For the original functor Φ_P, the inverse rotation of the unit-cone triangle is conventionally called the dual twist triangle

dualTwist ⟶ id_Y ⟶ Φ_Q ⋙ Φ_P ⟶ dualTwist⟦1⟧.

The implementation introduces no second cone or normalization mechanism. LeftAdjointKernelData.toRightAdjointKernelData reads the same adjunction as a right adjunction for Φ_Q, and all constructions below delegate to the right-adjunction unit/cotwist interface with the two correspondences swapped. The public names here retain the dual-twist convention of the original functor.

The ordinary unit-kernel arrow, its enhanced representative, and its cone are still supplied or selected noncanonically. Nothing here makes the dual twist exact, invertible, canonical, or spherical, and no dual-cotwist construction is bundled into this lane.

@[reducible, inline]
abbrev CategoryTheory.Triangulated.FourierMukai.DualTwistKernelData {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] (C : Correspondence X Y W₁) (C' : Correspondence Y X W₂) (E : Correspondence Y Y W) (P : W₁) (L : LeftAdjointKernelData C C' P) (D : ConvolutionData C' C E) (U : UnitKernelData E) :
Type vW

An ordinary kernel arrow realizing the unit of a kernel-presented left adjunction, named as the dual-twist input for the original functor.

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    @[reducible, inline]
    abbrev CategoryTheory.Triangulated.FourierMukai.DualTwistKernelConeData {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] (C : Correspondence X Y W₁) (C' : Correspondence Y X W₂) (E : Correspondence Y Y W) (e : Enhancement W) (P : W₁) (L : LeftAdjointKernelData C C' P) (D : ConvolutionData C' C E) (U : UnitKernelData E) :
    Type (max uE vE)

    An enhanced representative and chosen cone for a left-adjunction unit kernel arrow, named as the dual-twist input for the original functor.

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      The specialized transform equation for the left-adjunction unit.

      noncomputable def CategoryTheory.Triangulated.FourierMukai.DualTwistKernelData.ofFull {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] {C : Correspondence X Y W₁} {C' : Correspondence Y X W₂} {E : Correspondence Y Y W} {P : W₁} {L : LeftAdjointKernelData C C' P} {D : ConvolutionData C' C E} {U : UnitKernelData E} [E.kernelTransform.Full] :
      DualTwistKernelData C C' E P L D U

      Fullness of the kernel transform is sufficient to realize the left-adjunction unit by an ordinary kernel morphism.

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        noncomputable def CategoryTheory.Triangulated.FourierMukai.DualTwistKernelData.toConeData {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] {C : Correspondence X Y W₁} {C' : Correspondence Y X W₂} {E : Correspondence Y Y W} {P : W₁} {L : LeftAdjointKernelData C C' P} {D : ConvolutionData C' C E} {U : UnitKernelData E} (S : DualTwistKernelData C C' E P L D U) (e : Enhancement W) :
        DualTwistKernelConeData C C' E e P L D U

        Choose a closed representative and dg cone for the dual-twist unit-kernel arrow. Both choices are noncanonical.

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          @[reducible, inline]
          abbrev CategoryTheory.Triangulated.FourierMukai.DualTwistKernelConeData.dualTwistCone {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] {C : Correspondence X Y W₁} {C' : Correspondence Y X W₂} {E : Correspondence Y Y W} {e : Enhancement W} {P : W₁} {L : LeftAdjointKernelData C C' P} {D : ConvolutionData C' C E} {U : UnitKernelData E} (S : DualTwistKernelConeData C C' E e P L D U) :

          The unshifted cone of the left-adjunction unit.

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            @[reducible, inline]
            noncomputable abbrev CategoryTheory.Triangulated.FourierMukai.DualTwistKernelConeData.dualTwist {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] {C : Correspondence X Y W₁} {C' : Correspondence Y X W₂} {E : Correspondence Y Y W} {e : Enhancement W} {P : W₁} {L : LeftAdjointKernelData C C' P} {D : ConvolutionData C' C E} {U : UnitKernelData E} (S : DualTwistKernelConeData C C' E e P L D U) [HasShift Y ℤ] :

            The choice-dependent ordinary dual twist: the pointwise [-1] shift of the selected left-unit cone transform.

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              @[reducible, inline]
              noncomputable abbrev CategoryTheory.Triangulated.FourierMukai.DualTwistKernelConeData.dualTwistKernel {X : Type uX} {Y : Type uY} {W₁ : Type u₁} {W₂ : Type u₂} {W : Type uW} [Category.{vX, uX} X] [Category.{vY, uY} Y] [Category.{v₁, u₁} W₁] [Category.{v₂, u₂} W₂] [Category.{vW, uW} W] {C : Correspondence X Y W₁} {C' : Correspondence Y X W₂} {E : Correspondence Y Y W} {e : Enhancement W} {P : W₁} {L : LeftAdjointKernelData C C' P} {D : ConvolutionData C' C E} {U : UnitKernelData E} (S : DualTwistKernelConeData C C' E e P L D U) :
              W

              The shifted enhanced cone kernel presenting the dual twist.

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                The dual twist is a kernel functor for the endocorrespondence on Y. This does not assert exactness or invertibility.

                The transported second map from Φ_Q ⋙ Φ_P to the unshifted dual-twist cone.

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                  The transported connecting map from the unshifted dual-twist cone to the shifted identity.

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                    The source-natural unshifted left-unit triangle on the target Y of the original functor Φ_P.

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                      The conventional dual-twist triangle, obtained by inverse rotation of the left-adjunction unit triangle.

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                        The first projection of the dual-twist triangle is strictly the dual twist.

                        At the natural-transformation level, the second map is strictly the left-adjunction unit.