ModuleQuotient.lean
Nyll.ValuedFieldTheory.Ramification.Herbrand.Quotient
25 declarations indexed from sourceView source ↗ Module documentation
Pure group theory for Herbrand towers
This file contains the completion-free finite-group bookkeeping used in the Herbrand quotient theorem and the quotient and tower filtration theorems. It packages the filtrations induced on a subgroup and on its quotient image, proves the exact cardinality factorization at every level, and records compatibility of Herbrand functions with transport along group equivalences.
The valued-field inputs of the quotient-depth and upper-numbering identities do not occur here. Valued-field endpoints combine these structural lemmas with ramification-number averaging; the inverse-function and upper-numbering statements are proved directly in the Hilbert-ramification Herbrand theorem module.
Declarations
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.subgroupFiltration
DocumentationThe filtration induced on a subgroup by intersection with every ambient lower group.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.subgroupFiltration_lower
DocumentationStates the theorem subgroupFiltration_lower.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.mem_subgroupFiltration_lower_iff
DocumentationStates the theorem mem_subgroupFiltration_lower_iff.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageFiltration
DocumentationThe pointwise image filtration on a quotient by a normal subgroup. This is not asserted to be the actual lower filtration of a valued quotient; that identification is precisely the content supplied by Herbrand's theorem.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageFiltration_lower
DocumentationStates the theorem quotientImageFiltration_lower.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.lowerToQuotientImageHom
DocumentationAt each level, the subgroup filtration is the kernel of the quotient map restricted to the corresponding ambient lower group.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.lowerToQuotientImageHom_surjective
DocumentationStates the theorem lowerToQuotientImageHom_surjective.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.lowerToQuotientImageKerEquiv
DocumentationThe kernel of the restricted quotient map is canonically the intersection filtration on H.
Source context 5 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.card_subgroupFiltration_mul_card_quotientImageFiltration
DocumentationExact level-cardinality factorization |F_n| = |F_n ∩ H| * |image(F_n)|.
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Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.transportEquiv
DocumentationTransport a lower ramification filtration across a group equivalence.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.transportEquiv_lower
DocumentationStates the theorem transportEquiv_lower.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.mem_transportEquiv_lower_iff
DocumentationStates the theorem mem_transportEquiv_lower_iff.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.lowerEquivTransportEquiv
DocumentationEvery integral level is carried to the corresponding transported level.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.card_lower_transportEquiv
DocumentationStates the theorem card_lower_transportEquiv.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.herbrandFunction_transportEquiv
DocumentationThe Herbrand function is invariant under transport across a group equivalence.
Source context 7 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
open _root_.RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration (
herbrandFunction
herbrandFunction_eq_of_card_lower_eq
) in
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.inverseHerbrandFunction_transportEquiv
DocumentationThe inverse Herbrand function is invariant under transport across a group equivalence.
Source context 7 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
open _root_.RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration (
herbrandFunction_inverseHerbrandFunction
herbrandFunction_strictMono
herbrandFunction_transportEquiv
inverseHerbrandFunction
) in
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageTransport
DocumentationThe quotient-image filtration, transported to any isomorphic model of the quotient group.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageTransport_lower
DocumentationStates the theorem quotientImageTransport_lower.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.subgroup_map_equiv_eq_iff_eq_comap
DocumentationMapping a subgroup across a group equivalence is inverse to pulling it back. This orientation is the one used by the fixed-field quotient map.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.transportEquiv_lower_eq_map
DocumentationStates the theorem transportEquiv_lower_eq_map.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.transportEquiv_lower_eq_iff
DocumentationStates the theorem transportEquiv_lower_eq_iff.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageTransport_lower_eq_iff
DocumentationEquality with a transported quotient-image level is exactly the usual map/comap formulation of a lower-quotient theorem.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.card_subgroupFiltration_mul_card_quotientImageTransport
DocumentationExact level-cardinality factorization after replacing the abstract quotient by any isomorphic group model.
Source context 6 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageTransport_herbrandFunction
DocumentationStates the theorem quotientImageTransport_herbrandFunction.
Source context 7 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
open _root_.RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration (
herbrandFunction
) in
RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration.quotientImageTransport_inverseHerbrandFunction
DocumentationStates the theorem quotientImageTransport_inverseHerbrandFunction.
Source context 7 commands
Surrounding namespaces, section variables, and local commands at this declaration.
noncomputable section
universe u v
namespace RamificationTheory.DiscreteValuationField
namespace AntitoneNormalSubgroupFiltration
variable {G : Type u} [Group G]
variable {G' : Type v} [Group G']
open _root_.RamificationTheory.DiscreteValuationField.AntitoneNormalSubgroupFiltration (
inverseHerbrandFunction
) in