ProCGroups.FoxDifferential.Completed.ProCIntegerCoefficients.FreeGroup.Fundamental
The principal declarations in this module are:
zcFreeGroupFoxBoundary_derivativeVectorThe boundary-map form of the completed Fox fundamental formula. -zcFreeGroupFoxBoundary_of_crossedHomConditional completed Fox boundary formula. Any completed crossed differential on a free group with the standard basis values satisfies the completed Fox boundary formula. -zcFreeGroupFoxDerivative_fundamental_formula_of_crossedHomConditional completed Fox fundamental formula. The finite Fox-Euler sum computed from any completed crossed differential with standard basis values is \([\psi(w)]-1\). -zcFreeGroupFoxDerivative_euler_formula_of_crossedHomThe explicit \([\psi(w)]-1\) form of the conditional completed Fox-Euler formula.
theorem zcFreeGroupFoxBoundary_derivativeVector
(ψ : FreeGroup X →* H) (w : FreeGroup X) :
zcFreeGroupFoxBoundary C ψ (zcFreeGroupFoxDerivativeVector C ψ w) =
zcCompletedGroupAlgebraBoundary C ψ wThe boundary-map form of the completed Fox fundamental formula.
Show Lean proof
by
let beta : ScalarCrossedHom (zcCompletedGroupAlgebraScalar C ψ)
(ZCCompletedGroupAlgebra C H) :=
(zcFreeGroupFoxDerivativeVector C ψ).mapLinear
(zcFreeGroupFoxBoundary C ψ)
have hbasis :
∀ x : X, beta (FreeGroup.of x) =
zcCompletedGroupAlgebraBoundary C ψ (FreeGroup.of x) := by
intro x
change zcFreeGroupFoxBoundary C ψ
(zcFreeGroupFoxDerivativeVector C ψ (FreeGroup.of x)) =
zcCompletedGroupAlgebraBoundary C ψ (FreeGroup.of x)
rw [zcFreeGroupFoxDerivativeVector_of, zcFreeGroupFoxBoundary_single]
have hbeta_eq :
beta =
freeCrossedHomWithCoeff
(A := ZCCompletedGroupAlgebra C H)
(zcCompletedGroupAlgebraScalar C ψ)
(fun x => zcCompletedGroupAlgebraBoundary C ψ (FreeGroup.of x)) := by
exact freeCrossedHomWithCoeff_unique
(A := ZCCompletedGroupAlgebra C H)
(zcCompletedGroupAlgebraScalar C ψ)
(fun x => zcCompletedGroupAlgebraBoundary C ψ (FreeGroup.of x))
beta hbasis
have hboundary_eq :
zcCompletedGroupAlgebraBoundary C ψ =
freeCrossedHomWithCoeff
(A := ZCCompletedGroupAlgebra C H)
(zcCompletedGroupAlgebraScalar C ψ)
(fun x => zcCompletedGroupAlgebraBoundary C ψ (FreeGroup.of x)) := by
exact freeCrossedHomWithCoeff_unique
(A := ZCCompletedGroupAlgebra C H)
(zcCompletedGroupAlgebraScalar C ψ)
(fun x => zcCompletedGroupAlgebraBoundary C ψ (FreeGroup.of x))
(zcCompletedGroupAlgebraBoundary C ψ) (by intro x; rfl)
exact congrArg
(fun d : ScalarCrossedHom (zcCompletedGroupAlgebraScalar C ψ)
(ZCCompletedGroupAlgebra C H) => d w)
(hbeta_eq.trans hboundary_eq.symm)
theorem zcFreeGroupFoxBoundary_of_crossedHom
(ψ : FreeGroup X →* H)
(delta : ScalarCrossedHom (zcCompletedGroupAlgebraScalar C ψ)
(ZCFreeFoxCoordinates C (X := X) (H := H)))
(hbasis :
∀ x : X, delta (FreeGroup.of x) =
Pi.single x (1 : ZCCompletedGroupAlgebra C H))
(w : FreeGroup X) :
zcFreeGroupFoxBoundary C ψ (delta w) =
zcCompletedGroupAlgebraBoundary C ψ wConditional completed Fox boundary formula. Any completed crossed differential on a free group with the standard basis values satisfies the completed Fox boundary formula.
Show Lean proof
by
have hdelta_eq :
delta = zcFreeGroupFoxDerivativeVector C ψ :=
zcFreeGroupFoxDerivativeVector_unique C ψ delta hbasis
rw [hdelta_eq]
exact zcFreeGroupFoxBoundary_derivativeVector C ψ w
theorem zcFreeGroupFoxDerivative_fundamental_formula_of_crossedHom
(ψ : FreeGroup X →* H)
(delta : ScalarCrossedHom (zcCompletedGroupAlgebraScalar C ψ)
(ZCFreeFoxCoordinates C (X := X) (H := H)))
(hbasis :
∀ x : X, delta (FreeGroup.of x) =
Pi.single x (1 : ZCCompletedGroupAlgebra C H))
(w : FreeGroup X) :
zcCompletedGroupAlgebraBoundary C ψ w =
∑ i : X,
delta w i * (zcGroupLike C H (ψ (FreeGroup.of i)) - 1)Conditional completed Fox fundamental formula. The finite Fox-Euler sum computed from any completed crossed differential with standard basis values is \([\psi(w)]-1\).
Show Lean proof
by
simpa [zcFreeGroupFoxBoundary_apply] using
(zcFreeGroupFoxBoundary_of_crossedHom C ψ delta hbasis w).symm
theorem zcFreeGroupFoxDerivative_euler_formula_of_crossedHom
(ψ : FreeGroup X →* H)
(delta : ScalarCrossedHom (zcCompletedGroupAlgebraScalar C ψ)
(ZCFreeFoxCoordinates C (X := X) (H := H)))
(hbasis :
∀ x : X, delta (FreeGroup.of x) =
Pi.single x (1 : ZCCompletedGroupAlgebra C H))
(w : FreeGroup X) :
zcGroupLike C H (ψ w) - 1 =
∑ i : X,
delta w i * (zcGroupLike C H (ψ (FreeGroup.of i)) - 1)The explicit \([\psi(w)]-1\) form of the conditional completed Fox-Euler formula.
Show Lean proof
by
have h := zcFreeGroupFoxDerivative_fundamental_formula_of_crossedHom
C ψ delta hbasis w
change zcGroupLike C H (ψ w) - 1 = _ at h
exact h
theorem zcFreeGroupFoxDerivative_fundamental_formula
(ψ : FreeGroup X →* H) (w : FreeGroup X) :
zcCompletedGroupAlgebraBoundary C ψ w =
∑ i : X,
zcFreeGroupFoxDerivative C ψ i w *
(zcGroupLike C H (ψ (FreeGroup.of i)) - 1)The completed Fox fundamental formula, also known as the completed Fox-Euler formula: \([\psi(w)]-1 = \sum_i (\partial w/\partial x_i)([\psi(x_i)]-1)\).
Show Lean proof
by
simpa [zcFreeGroupFoxBoundary_apply, zcFreeGroupFoxDerivative] using
(zcFreeGroupFoxBoundary_derivativeVector C ψ w).symm
theorem zcFreeGroupFoxDerivative_euler_formula
(ψ : FreeGroup X →* H) (w : FreeGroup X) :
zcGroupLike C H (ψ w) - 1 =
∑ i : X,
zcFreeGroupFoxDerivative C ψ i w *
(zcGroupLike C H (ψ (FreeGroup.of i)) - 1)The explicit \([\psi(w)]-1\) form of the completed Fox-Euler formula.
Show Lean proof
by
have h := zcFreeGroupFoxDerivative_fundamental_formula C ψ w
change zcGroupLike C H (ψ w) - 1 = _ at h
exact h