Module

QuotientKernelBasis.lean

Nyll.ProCGroups.FoxDifferential.Completed.FreeProC.QuotientKernelBasis
4 declarations indexed from sourceView source ↗

Fox differential: completed — free pro-\(C\) — quotient kernel basis

The principal declarations in this module are:

  • HasIdentityQuotientKernelNeighbourhoodBasis

Quotient kernels form a neighborhood basis at the identity. For every open neighborhood of 1, some finite-stage kernel is contained in it. In a topological group this is the natural form obtained from finite quotient separation; it implies the left-coset basis used by subset_closure_of_quotientKernel_approximation.

  • HasIdentityQuotientKernelNeighbourhoodBasis.to_left

Identity-neighborhood quotient kernels give the left quotient-kernel basis.

  • subset_closure_of_identityQuotientKernel_approximation

Closure criterion using identity-neighborhood quotient kernels directly.

  • subset_closure_of_identityQuotientKernel_stage_exact

The closure criterion with identity-neighborhood quotient kernels can be checked at finite stages.

Declarations

FoxDifferential.HasIdentityQuotientKernelNeighbourhoodBasis

Quotient kernels form a neighborhood basis at the identity. For every open neighborhood of 1, some finite-stage kernel is contained in it. In a topological group this is the natural form obtained from finite quotient separation; it implies the left-coset basis used by subset_closure_of_quotientKernel_approximation.

Source context 8 commands

Surrounding namespaces, section variables, and local commands at this declaration.

namespace FoxDifferential
noncomputable section
open scoped Topology
universe u v
section QuotientKernelIdentityBasis
variable {Y : Type u} [Group Y] [TopologicalSpace Y]
variable {J : Type v} {Q : J → Type*} [∀ j, Group (Q j)]
variable (π : ∀ j : J, Y →* Q j)
def HasIdentityQuotientKernelNeighbourhoodBasis : Prop
FoxDifferential.HasIdentityQuotientKernelNeighbourhoodBasis.to_left

Identity-neighborhood quotient kernels give the left quotient-kernel basis.

Source context 8 commands

Surrounding namespaces, section variables, and local commands at this declaration.

namespace FoxDifferential
noncomputable section
open scoped Topology
universe u v
section QuotientKernelIdentityBasis
variable {Y : Type u} [Group Y] [TopologicalSpace Y]
variable {J : Type v} {Q : J → Type*} [∀ j, Group (Q j)]
variable (π : ∀ j : J, Y →* Q j)
theorem HasIdentityQuotientKernelNeighbourhoodBasis.to_left
    [IsTopologicalGroup Y]
    (hbasis : HasIdentityQuotientKernelNeighbourhoodBasis (Y := Y) π) :
    HasLeftQuotientKernelNeighbourhoodBasis (Y := Y) π
FoxDifferential.subset_closure_of_identityQuotientKernel_approximation

Closure criterion using identity-neighborhood quotient kernels directly.

Source context 8 commands

Surrounding namespaces, section variables, and local commands at this declaration.

namespace FoxDifferential
noncomputable section
open scoped Topology
universe u v
section QuotientKernelIdentityBasis
variable {Y : Type u} [Group Y] [TopologicalSpace Y]
variable {J : Type v} {Q : J → Type*} [∀ j, Group (Q j)]
variable (π : ∀ j : J, Y →* Q j)
theorem subset_closure_of_identityQuotientKernel_approximation
    [IsTopologicalGroup Y]
    {S T : Set Y}
    (hbasis : HasIdentityQuotientKernelNeighbourhoodBasis (Y := Y) π)
    (happrox :
      ∀ y : Y, y ∈ T → ∀ j : J,
        ∃ s : Y, s ∈ S ∧ π j s = π j y) :
    T ⊆ closure S
FoxDifferential.subset_closure_of_identityQuotientKernel_stage_exact

The closure criterion with identity-neighborhood quotient kernels can be checked at finite stages.

Source context 8 commands

Surrounding namespaces, section variables, and local commands at this declaration.

namespace FoxDifferential
noncomputable section
open scoped Topology
universe u v
section QuotientKernelIdentityBasis
variable {Y : Type u} [Group Y] [TopologicalSpace Y]
variable {J : Type v} {Q : J → Type*} [∀ j, Group (Q j)]
variable (π : ∀ j : J, Y →* Q j)
theorem subset_closure_of_identityQuotientKernel_stage_exact
    [IsTopologicalGroup Y]
    {S T : Set Y}
    (hbasis : HasIdentityQuotientKernelNeighbourhoodBasis (Y := Y) π)
    (Sstage Tstage : ∀ j : J, Set (Q j))
    (hTstage : ∀ y : Y, y ∈ T → ∀ j : J, π j y ∈ Tstage j)
    (hstage_exact : ∀ j : J, Tstage j ⊆ Sstage j)
    (hlift_stage : ∀ j : J, ∀ q : Q j, q ∈ Sstage j →
      ∃ s : Y, s ∈ S ∧ π j s = q) :
    T ⊆ closure S