The dual of a module object #
Substrate for Deligne (2002), §2.8: over a monoidal category D, an
exact pairing (X, Y) transports a module structure on X (for a
monoid object A) to its dual Y.
actCoev: the coevaluation twisted by the action,A ⟶ X ⊗ Y, with unit and multiplication lawsone_actCoev/mul_actCoev.dualActRight: the contragredient right actionY ⊗ A ⟶ Y, the mate of the action under the pairing; right-module laws aredualActRight_oneanddualActRight_dualActRight. No braiding is needed at this stage.dualActRight_evaluation/coevaluation_dualActRight: the mate calculus carrying the dual action across the evaluation and the coevaluation of the pairing.dualActLeft: in a braided category,(β_ Y A).inv ≫ dualActRight; for a commutative monoid this is a left module structure, bundled asdualModObj/dualMod. The inverse braiding is chosen so that the braided right actionactRightderived on the dual is exactlydualActRight(actRight_dualMod), which makes the pairing descend through the module-tensor coequalizer on the nose.modPairing : modTensor A (dualMod A X Y) (asMod A X) ⟶ A, the descent ofε_ X Y ≫ η[A]. It is balanced but is not a morphism ofA-modules for a general module; the equivariance that does hold iswhiskerLeft_modTensorπ_act_modPairing.modCopairing : A ⟶ modTensor A (asMod A X) (dualMod A X Y), the twisted coevaluation followed by the projection. It is a morphism of modules (mul_modCopairing), bundled asmodCopairingHom.
Zigzag identities at the modTensor level, and nonvanishing of the
copairing, need the multi-tensor coherence layer and are outside
this module's scope.
The coevaluation twisted by the action: informally
a ↦ (a • xᵢ) ⊗ yᵢ in dual-basis notation.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The twisted coevaluation, unfolded.
Uncurrying the twisted coevaluation recovers the action.
Uncurrying the twisted coevaluation recovers the action.
Unit law of the twisted coevaluation.
Unit law of the twisted coevaluation.
Multiplication law of the twisted coevaluation.
Multiplication law of the twisted coevaluation.
The contragredient right action on the dual: informally
f ⊗ a ↦ f (a • ·), that is, f ⊗ a ↦ f (a • xᵢ) yᵢ in dual-basis
notation.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The contragredient right action, unfolded.
Evaluation compatibility: the contragredient action against the evaluation is the original action across the pairing. This is the workhorse identity of the mate calculus.
Evaluation compatibility: the contragredient action against the evaluation is the original action across the pairing. This is the workhorse identity of the mate calculus.
Coevaluation compatibility, the mirror of
dualActRight_evaluation: inserting the coevaluation and applying
the contragredient action is the twisted coevaluation.
Coevaluation compatibility, the mirror of
dualActRight_evaluation: inserting the coevaluation and applying
the contragredient action is the twisted coevaluation.
Unitality of the contragredient right action.
Unitality of the contragredient right action.
Associativity of the contragredient right action.
Associativity of the contragredient right action.
The dual left action: the contragredient right action pulled
back along the inverse braiding. The inverse braiding (rather than
the braiding β_ A Y) is chosen so that the braided right action
actRight derived from it is exactly dualActRight; see
actRight_dualMod.
Equations
- RS.dualActLeft A X Y = CategoryTheory.CategoryStruct.comp (β_ Y A).inv (RS.dualActRight A X Y)
Instances For
The dual left action, unfolded.
Unitality of the dual left action.
Unitality of the dual left action.
Evaluation compatibility for the dual left action.
Evaluation compatibility for the dual left action.
Associativity of the dual left action, for a commutative monoid.
Associativity of the dual left action, for a commutative monoid.
The dual module structure on Y, for a commutative monoid.
Equations
- RS.dualModObj A X Y = { smul := RS.dualActLeft A X Y, one_smul := ⋯, mul_smul := ⋯ }
Instances For
The dual of a module, bundled: Y with the transported
action.
Equations
- RS.dualMod A X Y = { X := Y, mod := RS.dualModObj A X Y }
Instances For
On the dual module the action is the dual left action.
On the dual module the braided right action is exactly the contragredient right action.
A module object, bundled as a module.
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The two coequalizer legs agree against the paired evaluation:
this is exactly dualActRight_evaluation, thanks to the inverse
braiding convention of dualActLeft.
The A-valued pairing on the module tensor of the dual with
the module: the descent of ε_ X Y ≫ η[A] through the coequalizer.
It is balanced but, for a general module, not a morphism of
A-modules; see whiskerLeft_modTensorπ_act_modPairing for the
equivariance it does satisfy.
Equations
- RS.modPairing A X Y = RS.modTensorDesc A (RS.dualMod A X Y) (RS.asMod A X) (CategoryTheory.CategoryStruct.comp (ε_ X Y) CategoryTheory.MonObj.one) ⋯
Instances For
Defining equation of the pairing.
Defining equation of the pairing.
The copairing into the module tensor of the module with its dual: the twisted coevaluation followed by the projection.
Equations
- RS.modCopairing A X Y = CategoryTheory.CategoryStruct.comp (RS.actCoev A X Y) (RS.modTensorπ A (RS.asMod A X) (RS.dualMod A X Y))
Instances For
The copairing carries the unit to the projected coevaluation.
The copairing carries the unit to the projected coevaluation.
Equivariance of the pairing: acting on the tensor product and
pairing equals braiding the scalar through and pairing against the
acted-on module. For a general module this is the strongest
compatibility available; the pairing is not A-linear.
Equivariance of the pairing: acting on the tensor product and
pairing equals braiding the scalar through and pairing against the
acted-on module. For a general module this is the strongest
compatibility available; the pairing is not A-linear.
The copairing is a morphism of modules.
The copairing is a morphism of modules.
The copairing, bundled as a morphism of modules out of the regular module.
Equations
- RS.modCopairingHom A X Y = CategoryTheory.Mod.Hom.mk' (RS.modCopairing A X Y) ⋯
Instances For
The dual left action, specialised to the right dual Xᘁ.
Equations
- RS.rightDualActLeft A X = RS.dualActLeft A X Xᘁ
Instances For
Unitality of the dual left action at the right dual.
Unitality of the dual left action at the right dual.
Associativity of the dual left action at the right dual.
Associativity of the dual left action at the right dual.
The dual module, specialised to the right dual Xᘁ.
Equations
- RS.rightDualMod A X = RS.dualMod A X Xᘁ