ProCGroups.FoxDifferential.Completed.CoefficientRings.CompletedGroupAlgebraModN.InClass.Augmentation
The principal declarations in this module are:
modNCompletedGroupAlgebraStageAugmentationInClassThe augmentation on one class-restricted residue-coefficient finite stage. -modNCompletedGroupAlgebraStageAugmentationInClass_ofThe class-indexed finite-stage \(n\)-modular augmentation sends every group-like basis element to \(1\). -modNCompletedGroupAlgebraStageAugmentationInClass_singleThe class-indexed finite-stage \(n\)-modular augmentation sends a singleton basis element to its coefficient. -modNCompletedGroupAlgebraStageAugmentationInClass_compatibleClass-indexed finite-stage \(n\)-modular augmentations are compatible with group-quotient transition maps.
def modNCompletedGroupAlgebraStageAugmentationInClass
(C : ProCGroups.FiniteGroupClass.{u}) (U : CompletedGroupAlgebraIndexInClass G C) :
ModNCompletedGroupAlgebraStageInClass n G C U →+* ModNCompletedCoeff n :=
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n)
(CompletedGroupAlgebraQuotientInClass G C U)
(1 : CompletedGroupAlgebraQuotientInClass G C U →* ModNCompletedCoeff n)The augmentation on one class-restricted residue-coefficient finite stage.
omit [Fact (0 < n)] in
@[simp]
theorem modNCompletedGroupAlgebraStageAugmentationInClass_of
(C : ProCGroups.FiniteGroupClass.{u}) (U : CompletedGroupAlgebraIndexInClass G C)
(q : CompletedGroupAlgebraQuotientInClass G C U) :
modNCompletedGroupAlgebraStageAugmentationInClass n G C U
(MonoidAlgebra.of (ModNCompletedCoeff n) _ q) = 1The class-indexed finite-stage \(n\)-modular augmentation sends every group-like basis element to \(1\).
Show Lean proof
by
change
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n)
(CompletedGroupAlgebraQuotientInClass G C U)
(1 : CompletedGroupAlgebraQuotientInClass G C U →*
ModNCompletedCoeff n)
(MonoidAlgebra.single q 1) = 1
rw [MonoidAlgebra.lift_single, MonoidHom.one_apply, one_smul]
omit [Fact (0 < n)] in
@[simp]
theorem modNCompletedGroupAlgebraStageAugmentationInClass_single
(C : ProCGroups.FiniteGroupClass.{u}) (U : CompletedGroupAlgebraIndexInClass G C)
(q : CompletedGroupAlgebraQuotientInClass G C U) (a : ModNCompletedCoeff n) :
modNCompletedGroupAlgebraStageAugmentationInClass n G C U
(MonoidAlgebra.single q a) = aThe class-indexed finite-stage \(n\)-modular augmentation sends a singleton basis element to its coefficient.
Show Lean proof
by
change
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n)
(CompletedGroupAlgebraQuotientInClass G C U)
(1 : CompletedGroupAlgebraQuotientInClass G C U →*
ModNCompletedCoeff n)
(MonoidAlgebra.single q a) = a
rw [MonoidAlgebra.lift_single, MonoidHom.one_apply, smul_eq_mul, mul_one]
omit [Fact (0 < n)] in
@[simp 900]
theorem modNCompletedGroupAlgebraStageAugmentationInClass_compatible
(C : ProCGroups.FiniteGroupClass.{u})
{U V : CompletedGroupAlgebraIndexInClass G C} (hUV : U ≤ V) :
(modNCompletedGroupAlgebraStageAugmentationInClass n G C U).comp
(modNCompletedGroupAlgebraTransitionInClass n G C hUV) =
modNCompletedGroupAlgebraStageAugmentationInClass n G C VClass-indexed finite-stage \(n\)-modular augmentations are compatible with group-quotient transition maps.
Show Lean proof
by
apply RingHom.ext
intro x
induction x using MonoidAlgebra.induction_linear with
| zero =>
simp only [map_zero]
| add x y hx hy =>
simp only [map_add, hx, hy]
| single q a =>
rw [RingHom.comp_apply]
change
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n)
(CompletedGroupAlgebraQuotientInClass G C U)
(1 : CompletedGroupAlgebraQuotientInClass G C U →*
ModNCompletedCoeff n)
(MonoidAlgebra.mapDomain
(OpenNormalSubgroupInClass.map
(C := C) (G := G)
(U := OrderDual.ofDual U) (V := OrderDual.ofDual V) hUV)
(MonoidAlgebra.single q a)) =
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n)
(CompletedGroupAlgebraQuotientInClass G C V)
(1 : CompletedGroupAlgebraQuotientInClass G C V →*
ModNCompletedCoeff n)
(MonoidAlgebra.single q a)
rw [MonoidAlgebra.mapDomain_single, MonoidAlgebra.lift_single,
MonoidAlgebra.lift_single, MonoidHom.one_apply, smul_eq_mul, mul_one]
simp
omit [Fact (0 < n)] in
@[simp 900]
theorem modNCompletedGroupAlgebraStageAugmentationInClass_comp_stageMap
(C : ProCGroups.FiniteGroupClass.{u}) (U : CompletedGroupAlgebraIndexInClass G C) :
(modNCompletedGroupAlgebraStageAugmentationInClass n G C U).comp
(modNCompletedGroupAlgebraStageMapInClass n G C U) =
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n) G
(1 : G →* ModNCompletedCoeff n)Composing the class-indexed finite-stage \(n\)-modular augmentation with the dense stage map gives the ordinary \(n\)-modular group-algebra augmentation.
Show Lean proof
by
apply RingHom.ext
intro x
induction x using MonoidAlgebra.induction_linear with
| zero =>
simp only [map_zero]
| add x y hx hy =>
simp only [map_add, hx, hy]
| single g a =>
rw [RingHom.comp_apply]
change
modNCompletedGroupAlgebraStageAugmentationInClass n G C U
(MonoidAlgebra.mapDomain
(openNormalSubgroupInClassProj (C := C) (G := G) U)
(MonoidAlgebra.single g a)) =
MonoidAlgebra.lift (ModNCompletedCoeff n) (ModNCompletedCoeff n) G
(1 : G →* ModNCompletedCoeff n) (MonoidAlgebra.single g a)
rw [MonoidAlgebra.mapDomain_single,
modNCompletedGroupAlgebraStageAugmentationInClass_single,
MonoidAlgebra.lift_single, MonoidHom.one_apply, smul_eq_mul, mul_one]
omit [Fact (0 < n)] in
@[simp 900]
theorem modNCompletedGroupAlgebraStageAugmentationInClass_comp_stageCoeffMap
(C : ProCGroups.FiniteGroupClass.{u}) (U : CompletedGroupAlgebraIndexInClass G C)
{m : ℕ} (hnm : n ∣ m) :
(modNCompletedGroupAlgebraStageAugmentationInClass n G C U).comp
(modNCompletedGroupAlgebraStageCoeffMapInClass
(n := n) (m := m) (G := G) C U hnm) =
(modNCompletedCoeffMap (n := n) (m := m) hnm).comp
(modNCompletedGroupAlgebraStageAugmentationInClass m G C U)Stage augmentations commute with coefficient reduction on class-restricted finite quotient stages.
Show Lean proof
by
apply RingHom.ext
intro x
induction x using MonoidAlgebra.induction_linear with
| zero =>
simp only [map_zero]
| add x y hx hy =>
simp only [map_add, hx, hy]
| single q a =>
rw [RingHom.comp_apply, RingHom.comp_apply,
modNCompletedGroupAlgebraStageCoeffMapInClass_single_apply,
modNCompletedGroupAlgebraStageAugmentationInClass_single,
modNCompletedGroupAlgebraStageAugmentationInClass_single]