Intertwining maps #
This file gives defines intertwining maps of representations (aka equivariant linear maps).
An unbundled version of IntertwiningMap.
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An intertwining map between two representations ρ and σ of the same monoid G is a map
between underlying modules which commutes with the G-actions.
- toFun : V → W
An underlying
A-linear map of the underlyingA-modules.
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An intertwining map constructed form the linear map and the fact that it is intertwining.
Equations
- LinearMap.intertwiningMap_of_isIntertwiningMap ρ σ f hf = { toLinearMap := f, isIntertwining' := ⋯ }
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Equations
- Representation.IntertwiningMap.instFunLike ρ σ = { coe := fun (f : ρ.IntertwiningMap σ) => f.toFun, coe_injective' := ⋯ }
Equations
- Representation.IntertwiningMap.instAdd ρ σ = { add := fun (f g : ρ.IntertwiningMap σ) => { toLinearMap := f.toLinearMap + g.toLinearMap, isIntertwining' := ⋯ } }
Equations
- Representation.IntertwiningMap.instSMulNat ρ σ = { smul := fun (n : ℕ) (f : ρ.IntertwiningMap σ) => { toLinearMap := n • f.toLinearMap, isIntertwining' := ⋯ } }
Equations
- One or more equations did not get rendered due to their size.
Equations
- Representation.IntertwiningMap.instNeg ρ σ = { neg := fun (f : ρ.IntertwiningMap σ) => { toLinearMap := -f.toLinearMap, isIntertwining' := ⋯ } }
Equations
- Representation.IntertwiningMap.instSub ρ σ = { sub := fun (f g : ρ.IntertwiningMap σ) => { toLinearMap := f.toLinearMap - g.toLinearMap, isIntertwining' := ⋯ } }
Equations
- Representation.IntertwiningMap.instSMulInt ρ σ = { smul := fun (z : ℤ) (f : ρ.IntertwiningMap σ) => { toLinearMap := z • f.toLinearMap, isIntertwining' := ⋯ } }
Equations
- One or more equations did not get rendered due to their size.
A coercion from intertwining maps to additive monoid homomorphisms.
Equations
- Representation.IntertwiningMap.coeFnAddMonoidHom ρ σ = { toFun := DFunLike.coe, map_zero' := ⋯, map_add' := ⋯ }
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The identity map, considered as an intertwining map from a representation to itself.
Equations
- Representation.IntertwiningMap.id ρ = { toLinearMap := LinearMap.id, isIntertwining' := ⋯ }
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Composition of intertwining maps.
A convenience variant of IntertwiningMap.llcomp for use in dot notation.
Equations
- f.comp g = { toLinearMap := f.toLinearMap ∘ₗ g.toLinearMap, isIntertwining' := ⋯ }
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Equivalence between representations is a bijective intertwining map.
- mk' :: (
- toFun : V → W
- invFun : W → V
- left_inv : Function.LeftInverse self.invFun (↑self).toFun
- right_inv : Function.RightInverse self.invFun (↑self).toFun
- )
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An Equiv between representations could be built from a LinearEquiv and an assumption
proving the G-equivariance.
Equations
- Representation.Equiv.mk e he = { toLinearMap := ↑e, isIntertwining' := he, invFun := e.invFun, left_inv := ⋯, right_inv := ⋯ }
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Equations
- Representation.Equiv.instEquivLike = { coe := fun (φ : ρ.Equiv σ) => ⇑φ.toLinearEquiv, inv := fun (φ : ρ.Equiv σ) => φ.invFun, left_inv := ⋯, right_inv := ⋯, coe_injective' := ⋯ }
Any representation is equivalent to itself.
Equations
- Representation.Equiv.refl ρ = { toLinearMap := ↑(LinearEquiv.refl A V), isIntertwining' := ⋯, invFun := (LinearEquiv.refl A V).invFun, left_inv := ⋯, right_inv := ⋯ }
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The equiv between representations are symmetric.
Equations
- φ.symm = { toLinearMap := ↑φ.toLinearEquiv.symm, isIntertwining' := ⋯, invFun := φ.toLinearEquiv.symm.invFun, left_inv := ⋯, right_inv := ⋯ }
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Composition of two Equiv.
Equations
- φ.trans ψ = { toLinearMap := ↑(φ.toLinearEquiv ≪≫ₗ ψ.toLinearEquiv), isIntertwining' := ⋯, invFun := (φ.toLinearEquiv ≪≫ₗ ψ.toLinearEquiv).invFun, left_inv := ⋯, right_inv := ⋯ }
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Equations
- Representation.IntertwiningMap.instSMul ρ σ = { smul := fun (a : A) (f : ρ.IntertwiningMap σ) => { toLinearMap := a • f.toLinearMap, isIntertwining' := ⋯ } }
Equations
- One or more equations did not get rendered due to their size.
An intertwining map is the same thing as a linear map over the group ring.
Equations
- One or more equations did not get rendered due to their size.
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Composition of intertwining maps.
Equations
- One or more equations did not get rendered due to their size.
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Equations
Equations
Equations
- Representation.IntertwiningMap.instSemigroup ρ = Function.Injective.semigroup (fun (f : ρ.IntertwiningMap ρ) => f.toLinearMap) ⋯ ⋯
Equations
- Representation.IntertwiningMap.instPowNat ρ = { pow := fun (f : ρ.IntertwiningMap ρ) (n : ℕ) => npowRecAuto n f }
Equations
- Representation.IntertwiningMap.instMonoid ρ = Function.Injective.monoid (fun (f : ρ.IntertwiningMap ρ) => f.toLinearMap) ⋯ ⋯ ⋯ ⋯
Equations
- One or more equations did not get rendered due to their size.
Equations
Intertwining maps from ρ to itself are the same as A[G]-linear endomorphisms.
Equations
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If g is a central element of a monoid G, then this is the action of g, considered as an
intertwining map from any representation of G to itself.
Equations
- Representation.IntertwiningMap.centralMul ρ g hg = { toLinearMap := ρ g, isIntertwining' := ⋯ }
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IntertwiningMap.toLinearMap as a linear map.
Equations
- Representation.IntertwiningMap.toLinearMapl ρ σ = { toFun := Representation.IntertwiningMap.toLinearMap, map_add' := ⋯, map_smul' := ⋯ }
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A bijective intertwining map is an equivalence of representations.
Equations
- One or more equations did not get rendered due to their size.
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The tensor product of intertwining maps induced from tensor product of linear maps.
Equations
- f.tensor g = { toLinearMap := TensorProduct.map f.toLinearMap g.toLinearMap, isIntertwining' := ⋯ }
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The intertwining map induced from f : σ → τ to ρ.tprod σ → ρ.tprod τ.
Equations
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The natural intertwining map σ.tprod ρ → τ.tprod ρ induced by f : σ → τ.
Equations
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Equivalence between representations induced from TensorProduct.comm.
Equations
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The Equiv between representations induced from TensorProduct.assoc.
Equations
- Representation.TensorProduct.assoc ρ σ τ = Representation.Equiv.mk (TensorProduct.assoc A V W U) ⋯
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The Equiv between representations induced from TensorProduct.rid.
Equations
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The Equiv between representations induced from TensorProduct.lid.
Equations
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dualTensorHom as an equivalence of representations.
Equations
- Representation.Equiv.dualTensorHom ρ σ = { toLinearMap := ↑(dualTensorHomEquiv k V W), isIntertwining' := ⋯, invFun := (dualTensorHomEquiv k V W).invFun, left_inv := ⋯, right_inv := ⋯ }