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Diff — Universal enveloping algebra

Revision #3102 → #3588 · back to history

modifiedUniversal enveloping algebra (informal)e27d99e4ed7f
FieldFrom #3102To #3588
noteThe universal enveloping algebra as an R-algebra is defined in Mathlib.Algebra.Lie.UniversalEnveloping.The universal enveloping algebra as an R-algebra is defined in Mathlib.Algebra.Lie.UniversalEnveloping (verified via decl_exists).
addedVerma modules as quotients of U(g)10408fbff5ad
modifiedU(g) via generators and relations3f5c39a64be6
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noteMathlib builds U(g) as the tensor algebra quotiented by the Lie-compatibility relation `UniversalEnvelopingAlgebra.Rel`, i.e. by exactly this generators/relations presentation.Mathlib builds U(g) as the tensor algebra quotiented by the Lie-compatibility relation `UniversalEnvelopingAlgebra.Rel.lie_compat`, matching this generators/relations presentation.
modifiedPBW basis spans U(g) (preview)5dad205518dd
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noteNo Poincaré–Birkhoff–Witt basis result appears in Mathlib (grep and loogle for `Birkhoff`/`PBW` return no hits).No Poincaré–Birkhoff–Witt basis result appears in Mathlib (grep for `PBW` returns no hits; `Birkhoff` matches unrelated results).
modifiedFormal definition of U(g) as a quotient063cf150569d
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note`UniversalEnvelopingAlgebra R L` is literally the quotient of the tensor algebra by the ring congruence generated by `Rel.lie_compat`.`UniversalEnvelopingAlgebra R L` is literally the `RingQuot` of the tensor algebra by the ring congruence generated by `Rel.lie_compat`.
addedLifted bracket is bilinear, skew-symmetric, and Jacobi56a17dc37ab3
modifiedU(g) as tensor algebra modulo two-sided ideal0ad887b2c82e
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mathlib.match_kindcloseexact
noteThis equivalent presentation as T(g)/I with I generated by x⊗y − y⊗x − [x,y] matches the `RingQuot` of `UniversalEnvelopingAlgebra.Rel` in Mathlib.The equivalent presentation as T(g)/I with I generated by x⊗y − y⊗x − [x,y] matches the `RingQuot` of `UniversalEnvelopingAlgebra.Rel.lie_compat`.
modifiedU for Lie superalgebras0ee6974adba8
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noteMathlib does not have Lie superalgebras (grep for `LieSuperalgebra` returns no files).Mathlib does not have Lie superalgebras (grep for `LieSuperalgebra`/`LieSuper` returns no files).
addedGeneralization to Malcev, Bol, and left alternative algebras1d210dd4e6ed
modifiedUniversal property of U(g)02ac0cc12702
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note`UniversalEnvelopingAlgebra.lift` gives the bijection between Lie-algebra maps `L →ₗ⁅R⁆ A` and algebra maps `U(L) →ₐ[R] A`, with uniqueness via `hom_ext`/`lift_unique`.`UniversalEnvelopingAlgebra.lift` gives the bijection between Lie-algebra maps `L →ₗ⁅R⁆ A` and algebra maps `U(L) →ₐ[R] A`, with uniqueness via `hom_ext`.
addedEvery g-representation extends uniquely to U(g)5d82b6cde160
addedFree Lie algebra basis via Hall/Lyndon wordseade2ddce52c
modifiedJordan algebra construction yields exterior algebra71de074ca3db
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noteMathlib has Jordan algebras and exterior algebras separately but no PBW-style relation between them.Mathlib has Jordan algebras (`Mathlib.Algebra.Jordan.Basic`) and exterior algebras separately but no PBW-style relation between them.
addedBerezin formula from Baker–Campbell–Hausdorff6033ad38d3d9
modifiedHeisenberg algebra and Weyl algebra (Moyal product)00f749f145d0
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noteNeither the Heisenberg Lie algebra nor the Weyl algebra is defined in Mathlib.Neither the Heisenberg Lie algebra nor the Weyl algebra is defined in Mathlib (grep for `Heisenberg`/`WeylAlgebra` returns no hits).
modifiedU of free Lie algebra is free associative algebra77c43eddbf40
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note`FreeLieAlgebra.universalEnvelopingEquivFreeAlgebra` gives the algebra equivalence `U(FreeLieAlgebra R X) ≃ₐ[R] FreeAlgebra R X`.`FreeLieAlgebra.universalEnvelopingEquivFreeAlgebra` gives the algebra equivalence `U(FreeLieAlgebra R X) ≃ₐ[R] FreeAlgebra R X` (verified via decl_exists).
modifiedCasimir operators as basis of center15f9ce1f5b42
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noteNo `Casimir` declarations in Mathlib (grep and loogle both return zero hits).No `Casimir` declarations in Mathlib (grep returns zero hits).
modifiedHarish-Chandra isomorphism for center of U(g)2c5921d9ed3a
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noteNo Harish-Chandra isomorphism in Mathlib (grep returns no hits).No Harish-Chandra isomorphism in Mathlib (grep for `HarishChandra`/`Harish-Chandra` returns no hits).
modifiedU(g) inherits Hopf algebra structure from tensor algebra02cbcbe8fe13
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note`HopfAlgebra` is defined in Mathlib but no `HopfAlgebra` instance is placed on `UniversalEnvelopingAlgebra`.`HopfAlgebra` is defined in Mathlib but no `HopfAlgebra` instance is placed on `UniversalEnvelopingAlgebra` (grep for `UniversalEnveloping.*Hopf` returns no hits).
modifiedGelfand–Naimark for commutative Hopf algebrasfa519f748cbe
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noteNo Gelfand–Naimark theorem for commutative Hopf algebras exists in Mathlib (grep for `GelfandNaimark` returns no hits).No Gelfand–Naimark theorem for commutative Hopf algebras exists in Mathlib (only `GelfandNaimarkSegal` on C*-algebras is present).