map and comap for Submodules #
Main declarations #
Submodule.map: The pushforward of a submodulep ⊆ Mbyf : M → M₂Submodule.comap: The pullback of a submodulep ⊆ M₂alongf : M → M₂Submodule.giMapComap:map fandcomap fform aGaloisInsertionwhenfis surjective.Submodule.gciMapComap:map fandcomap fform aGaloisCoinsertionwhenfis injective.
Tags #
submodule, subspace, linear map, pushforward, pullback
The pushforward of a submodule p ⊆ M by f : M → M₂
Equations
- Submodule.map f p = let __src := AddSubmonoid.map f p.toAddSubmonoid; { carrier := ⇑f '' ↑p, add_mem' := ⋯, zero_mem' := ⋯, smul_mem' := ⋯ }
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The pushforward of a submodule by an injective linear map is
linearly equivalent to the original submodule. See also LinearEquiv.submoduleMap for a
computable version when f has an explicit inverse.
Equations
- Submodule.equivMapOfInjective f i p = let __src := Equiv.Set.image (⇑f) (↑p) i; { toFun := __src.toFun, map_add' := ⋯, map_smul' := ⋯, invFun := __src.invFun, left_inv := ⋯, right_inv := ⋯ }
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The pullback of a submodule p ⊆ M₂ along f : M → M₂
Equations
- Submodule.comap f p = let __src := AddSubmonoid.comap f p.toAddSubmonoid; { carrier := ⇑f ⁻¹' ↑p, add_mem' := ⋯, zero_mem' := ⋯, smul_mem' := ⋯ }
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map f and comap f form a GaloisInsertion when f is surjective.
Equations
- Submodule.giMapComap hf = ⋯.toGaloisInsertion ⋯
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map f and comap f form a GaloisCoinsertion when f is injective.
Equations
- Submodule.gciMapComap hf = ⋯.toGaloisCoinsertion ⋯
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A linear isomorphism induces an order isomorphism of submodules.
Equations
- Submodule.orderIsoMapComapOfBijective f hf = { toFun := Submodule.map f, invFun := Submodule.comap f, left_inv := ⋯, right_inv := ⋯, map_rel_iff' := ⋯ }
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A linear isomorphism induces an order isomorphism of submodules.
Equations
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The infimum of a family of invariant submodule of an endomorphism is also an invariant submodule.
If s ≤ t, then we can view s as a submodule of t by taking the comap
of t.subtype.
Equations
- One or more equations did not get rendered due to their size.
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Given modules M, M₂ over a commutative ring, together with submodules p ⊆ M, q ⊆ M₂,
the set of maps $\{f ∈ Hom(M, M₂) | f(p) ⊆ q \}$ is a submodule of Hom(M, M₂).
Equations
- pₗ.compatibleMaps qₗ = { carrier := {fₗ : N →ₗ[R] N₂ | pₗ ≤ Submodule.comap fₗ qₗ}, add_mem' := ⋯, zero_mem' := ⋯, smul_mem' := ⋯ }
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A linear map between two modules restricts to a linear map from any submodule p of the domain onto the image of that submodule.
This is the linear version of AddMonoidHom.addSubmonoidMap and AddMonoidHom.addSubgroupMap.
Equations
- f.submoduleMap p = f.restrict ⋯
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Linear equivalences #
A linear equivalence of two modules restricts to a linear equivalence from any submodule
p of the domain onto the image of that submodule.
This is the linear version of AddEquiv.submonoidMap and AddEquiv.subgroupMap.
This is LinearEquiv.ofSubmodule' but with map on the right instead of comap on the left.
Equations
- One or more equations did not get rendered due to their size.