OAI/NumberTheory/DukePrimeDegree/Geometry/MatrixConjugationDensity.lean
11 declarations, 0 contain sorry, 0 declared as axioms
Finite measures in the matrix conjugation representation
This is the elementary recurrence part of the needed Borel-density argument. A finite measure invariant under a strict real contraction is concentrated at zero. Applied to matrix coefficients, split diagonal conjugation forces invariant finite matrix measures onto diagonal matrices.
- theorem
OAI.DukePrimeDegree.ae_zero_of_mul_map_eqline 28 - def
OAI.DukePrimeDegree.diagonalMatrixConjugationline 52Source documentation
Conjugation by the split real diagonal one-parameter subgroup.
def diagonalMatrixConjugation {n : ℕ} (ell : Fin n → ℝ) (t : ℝ) (M : Matrix (Fin n) (Fin n) ℝ) : Matrix (Fin n) (Fin n) ℝ := … - lemma
OAI.DukePrimeDegree.diagonalMatrixConjugation_entryline 57 - lemma
OAI.DukePrimeDegree.continuous_diagonalMatrixConjugationline 65 - theorem
OAI.DukePrimeDegree.ae_matrix_entry_zero_of_split_invarianceline 76Source documentation
Split diagonal invariance annihilates every nonzero weight.
theorem ae_matrix_entry_zero_of_split_invariance {n : ℕ} (μ : Measure (Matrix (Fin n) (Fin n) ℝ)) [IsFiniteMeasure μ] (ell : Fin n → ℝ) (hdiag : ∀ t : ℝ, μ.map (diagonalMatrixConjugation ell t) = μ) (i j : Fin n) (hij : ell i ≠ ell j) : ∀ᵐ M ∂μ, M i j = 0 := by … - theorem
OAI.DukePrimeDegree.ae_diagonal_of_split_invarianceline 105Source documentation
For a regular split diagonal subgroup, an invariant finite matrix measure is supported on the diagonal matrix space.
theorem ae_diagonal_of_split_invariance {n : ℕ} (μ : Measure (Matrix (Fin n) (Fin n) ℝ)) [IsFiniteMeasure μ] (ell : Fin n → ℝ) (hell : Function.Injective ell) (hdiag : ∀ t : ℝ, μ.map (diagonalMatrixConjugation ell t) = μ) : ∀ᵐ M ∂μ, M = Matrix.diagonal (fun i => M i i) := by … - def
OAI.DukePrimeDegree.rootMatrixConjugationline 127Source documentation
Conjugation by a root unipotent matrix.
def rootMatrixConjugation {n : ℕ} (i j : Fin n) (t : ℝ) (M : Matrix (Fin n) (Fin n) ℝ) : Matrix (Fin n) (Fin n) ℝ := … - lemma
OAI.DukePrimeDegree.continuous_rootMatrixConjugationline 131 - theorem
OAI.DukePrimeDegree.ae_diagonal_entries_eq_of_root_invarianceline 138Source documentation
Once the matrix measure is diagonal, one invariant root forces the two corresponding diagonal entries to coincide.
theorem ae_diagonal_entries_eq_of_root_invariance {n : ℕ} (μ : Measure (Matrix (Fin n) (Fin n) ℝ)) (hD : ∀ᵐ M ∂μ, M = Matrix.diagonal (fun i => M i i)) (i j : Fin n) (hij : i ≠ j) (hroot : μ.map (rootMatrixConjugation i j 1) = μ) : ∀ᵐ M ∂μ, M i i = M j j := by … - theorem
OAI.DukePrimeDegree.ae_blockScalar_of_conjugation_invarianceline 170Source documentation
Finite matrix measures invariant under split diagonals and the within-block root groups are concentrated on the block-scalar algebra.
theorem ae_blockScalar_of_conjugation_invariance {n : ℕ} (μ : Measure (Matrix (Fin n) (Fin n) ℝ)) [IsFiniteMeasure μ] (ell : Fin n → ℝ) (hell : Function.Injective ell) (hdiag : ∀ t : ℝ, μ.map (diagonalMatrixConjugation ell t) = μ) (r : Setoid (Fin n)) (hroot : ∀ i j, i ≠ j → r i j → μ.map (rootMatrixConjugation i j 1) = μ) : ∀ᵐ M ∂μ, M ∈ blockScalarAlgebra r := by …Mentions: OAI.DukePrimeDegree.diagonalMatrixConjugation, OAI.DukePrimeDegree.rootMatrixConjugation, OAI.DukePrimeDegree.blockScalarAlgebra
- theorem
OAI.DukePrimeDegree.support_subset_blockScalar_of_conjugation_invarianceline 195Source documentation
The same conclusion holds at every point of the measure's support. This is the form used by a continuous conjugation-orbit map.
theorem support_subset_blockScalar_of_conjugation_invariance {n : ℕ} (μ : Measure (Matrix (Fin n) (Fin n) ℝ)) [IsFiniteMeasure μ] (ell : Fin n → ℝ) (hell : Function.Injective ell) (hdiag : ∀ t : ℝ, μ.map (diagonalMatrixConjugation ell t) = μ) (r : Setoid (Fin n)) (hroot : ∀ i j, i ≠ j → r i j → μ.map (rootMatrixConjugation i j 1) = μ) : μ.support ⊆ (blockScalarAlgebra r : Set (Matrix (Fin n) (Fin n) ℝ)) := by …Mentions: OAI.DukePrimeDegree.diagonalMatrixConjugation, OAI.DukePrimeDegree.rootMatrixConjugation, OAI.DukePrimeDegree.blockScalarAlgebra