The `deg Φ`-th iterate of the Frobenius is the identity;
ProvedTypeDensity.frobenius_pow_degree_eq_idtype-density
The deg Φ-th iterate of the Frobenius is the identity; in particular the Frobenius is bijective.
Preamble
import Definitions.Def_TypeDensity_Basic import Definitions.Def_TypeDensity_Formula_LawAlgebra import Definitions.Def_TypeDensity_Algebra_AlgebraType import Definitions.Def_TypeDensity_Measure_AdicCylinders import Definitions.Def_TypeDensity_Measure_HenselProducts import Definitions.Def_TypeDensity_Unramified_Extension import Definitions.Def_TypeDensity_Measure_PrimitiveLocus import Definitions.Def_TypeDensity_Algebra_FactorInvariant import Theorems.Thm_TypeDensity_unramified_adic_complete import Theorems.Thm_TypeDensity_simple_root_derivative_unit import Theorems.Thm_TypeDensity_frobenius_residue_action import Theorems.Thm_TypeDensity_residue_extension_field import Mathlib.FieldTheory.RatFunc.Basic import Mathlib.MeasureTheory.Measure.Haar.Unique import Mathlib.NumberTheory.ArithmeticFunction.Moebius import Mathlib.NumberTheory.Padics.PadicIntegers import Mathlib.RingTheory.IntegralClosure.IntegralRestrict import Mathlib.RingTheory.MvPowerSeries.Basic import Mathlib.RingTheory.RamificationInertia.Basic import Mathlib.Topology.Algebra.Nonarchimedean.AdicTopology import Mathlib.FieldTheory.Finite.GaloisField import Mathlib.RingTheory.AdicCompletion.Algebra import Mathlib.RingTheory.RegularLocalRing.Defs import Mathlib.RingTheory.Henselian import Mathlib.Topology.Algebra.MvPolynomial import Mathlib.Algebra.Group.Pi.Units import Mathlib.Order.CompletePartialOrder import Mathlib.RingTheory.Polynomial.Resultant.Basic import Mathlib.RingTheory.SimpleRing.Principal import Mathlib.Algebra.GroupWithZero.Submonoid.CancelMulZero import Mathlib.Algebra.Module.StablyFree.Basic import Mathlib.NumberTheory.Padics.RingHoms set_option autoImplicit false open TypeDensity open scoped BigOperators ENNReal
Formal statement
theorem TypeDensity.frobenius_pow_degree_eq_id (O : Type) [CommRing O] [IsLocalRing O]
[IsAdicComplete (IsLocalRing.maximalIdeal O) O] [Finite (IsLocalRing.ResidueField O)]
(Φ : Polynomial O) (hΦ : IsUnramifiedLift O Φ) :
frobeniusIter O Φ Φ.natDegree = AlgHom.id O (AdjoinRoot Φ) ∧
Function.Bijective (unramifiedFrobenius O Φ) := by sorrySource
TypeDensity/Unramified/FrobeniusDescent.lean#L572-L616