Add Equiv Add Haar Char eq ring Haar Char det diagonal
MeasureTheory.addEquivAddHaarChar_eq_ringHaarChar_det_diagonal
Plain-language statement
A diagonal matrix scales addHaar with its determinant
Exact Lean statement
lemma addEquivAddHaarChar_eq_ringHaarChar_det_diagonal [SecondCountableTopology F]
(ρ : (ι → F) ≃L[F] (ι → F)) {D : ι → F}
(h : ρ.toLinearMap.toMatrix' = Matrix.diagonal D) :
addEquivAddHaarChar ρ.toContinuousAddEquiv = ringHaarChar ρ.toLinearEquiv.detFormal artifact
Lean source
lemma addEquivAddHaarChar_eq_ringHaarChar_det_diagonal [SecondCountableTopology F] (ρ : (ι → F) ≃L[F] (ι → F)) {D : ι → F} (h : ρ.toLinearMap.toMatrix' = Matrix.diagonal D) : addEquivAddHaarChar ρ.toContinuousAddEquiv = ringHaarChar ρ.toLinearEquiv.det := by have feq : ρ.toLinearMap = Matrix.toLin' (Matrix.diagonal D) := by rw [← h, Matrix.toLin'_toMatrix'] have fdet : ρ.toLinearMap.det = ∏ i, D i := by rw [feq, LinearMap.det_toLin', det_diagonal] have hu (i : ι) : IsUnit (D i) := by refine IsUnit.prod_univ_iff.1 ?_ i rw [← fdet] exact LinearEquiv.isUnit_det' ρ.toLinearEquiv -- `ρ` acts coordinatewise as left multiplication by the units `D i`, so both sides equal -- `∏ i, ringHaarChar (D i)`: the left via `piCongrRight`, the right since `det ρ = ∏ i, D i`. have hρ : ρ.toContinuousAddEquiv = .piCongrRight fun i ↦ .mulLeft (hu i).unit := by ext x i calc ρ.toContinuousAddEquiv x i = Matrix.toLin' (Matrix.diagonal D) x i := by rw [← feq]; rfl _ = D i * x i := mulVec_diagonal D x i have hdet : ρ.toLinearEquiv.det = ∏ i, (hu i).unit := by apply Units.val_inj.1 simpa [LinearEquiv.coe_det] using fdet rw [hρ, addEquivAddHaarChar_piCongrRight, hdet, map_prod] rfl- Project
- Fermat's Last Theorem
- License
- Apache-2.0
- Commit
- 8dd808888295
- Source
- FLT/HaarMeasure/HaarChar/FiniteDimensional.lean:64-85
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