OAI/Analysis/TraceCone/StrongDensity.lean

GitHub source file

94 declarations, 0 contain sorry, 0 declared as axioms

Strong density in operator algebras

Finite-vector bicommutant density, contractive Kaplansky approximation and strong-star approximation in nonunital weak operator closures.

  1. abbrev OAI.TraceConeClassification.HilbertTuple line 21
  2. abbrev OAI.TraceConeClassification.diagonalOp line 23
  3. lemma OAI.TraceConeClassification.diagonalOp_apply line 26
  4. lemma OAI.TraceConeClassification.diagonalOp_star line 29
  5. abbrev OAI.TraceConeClassification.diagonalHom line 38
  6. abbrev OAI.TraceConeClassification.tupleInclusion line 41
  7. lemma OAI.TraceConeClassification.tupleInclusion_apply line 45
  8. lemma OAI.TraceConeClassification.tuple_decomposition line 50
  9. lemma OAI.TraceConeClassification.diagonalOp_inclusion line 55
  10. abbrev OAI.TraceConeClassification.matrixEntry line 61
  11. lemma OAI.TraceConeClassification.matrixEntry_apply line 65
  12. lemma OAI.TraceConeClassification.diagonal_bicommutant line 68
  13. theorem OAI.TraceConeClassification.bicommutant_strong_density line 75

    Source documentation

    The finite-vector form of strong-operator density in the bicommutant.

    theorem bicommutant_strong_density
        (A : StarSubalgebra ℂ (H →L[ℂ] H)) (T : H →L[ℂ] H)
        (hT : T ∈ Set.centralizer (Set.centralizer (A : Set (H →L[ℂ] H))))
        (n : ℕ) (ξ : Fin n → H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a ∈ A, ∀ i, ‖a (ξ i) - T (ξ i)‖ < ε := by
    …
  14. lemma OAI.TraceConeClassification.bicommutant_approximating_sequence line 87
  15. theorem OAI.TraceConeClassification.bicommutant_selfadjoint_strong_density line 102

    Source documentation

    Self-adjoint strong density is needed before the contractive functional-calculus step.

    theorem bicommutant_selfadjoint_strong_density
        (A : StarSubalgebra ℂ (H →L[ℂ] H)) (T : H →L[ℂ] H)
        (hT : T ∈ Set.centralizer (Set.centralizer (A : Set (H →L[ℂ] H))))
        (hsa : IsSelfAdjoint T) (n : ℕ) (ξ : Fin n → H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a ∈ A, IsSelfAdjoint a ∧ ∀ i, ‖a (ξ i) - T (ξ i)‖ < ε := by
    …
  16. def OAI.TraceConeClassification.densityG line 114

    Source documentation

    Rational functions used to obtain bounded approximants without bounded input norms.

    def densityG (t : ℝ) : ℝ := (1 + t^2)⁻¹
  17. def OAI.TraceConeClassification.densityH line 115
  18. def OAI.TraceConeClassification.densityF line 116
  19. def OAI.TraceConeClassification.densityK line 117
  20. lemma OAI.TraceConeClassification.density_den_pos line 119
  21. lemma OAI.TraceConeClassification.densityG_cont line 120
  22. lemma OAI.TraceConeClassification.densityH_cont line 122
  23. lemma OAI.TraceConeClassification.densityF_cont line 125
  24. lemma OAI.TraceConeClassification.densityK_cont line 126
  25. lemma OAI.TraceConeClassification.densityG_bound line 131
  26. lemma OAI.TraceConeClassification.densityH_bound line 134
  27. lemma OAI.TraceConeClassification.densityF_bound line 138
  28. lemma OAI.TraceConeClassification.density_FK line 144
  29. def OAI.TraceConeClassification.densityg line 156
  30. def OAI.TraceConeClassification.densityh line 157
  31. def OAI.TraceConeClassification.densityf line 158
  32. lemma OAI.TraceConeClassification.densityg_norm line 160
  33. lemma OAI.TraceConeClassification.densityh_norm line 162
  34. lemma OAI.TraceConeClassification.densityf_norm line 164
  35. lemma OAI.TraceConeClassification.densityf_eq line 166
  36. lemma OAI.TraceConeClassification.density_selfadjoint line 168
  37. lemma OAI.TraceConeClassification.densityg_mul line 170
  38. lemma OAI.TraceConeClassification.mul_densityg line 178
  39. lemma OAI.TraceConeClassification.densityh_mul line 182
  40. lemma OAI.TraceConeClassification.mul_densityh line 194
  41. lemma OAI.TraceConeClassification.densityh_difference line 199
  42. lemma OAI.TraceConeClassification.density_FK_operator line 209
  43. lemma OAI.TraceConeClassification.densityh_apply_difference line 224
  44. theorem OAI.TraceConeClassification.kaplansky_selfadjoint line 245

    Source documentation

    Contractive self-adjoint Kaplansky approximation, with actual construction from the double commutant and no bound assumed on the initial approximants.

    theorem kaplansky_selfadjoint
        (A : StarSubalgebra ℂ (H →L[ℂ] H)) (hclosed : IsClosed (A : Set (H →L[ℂ] H)))
        (T : H →L[ℂ] H)
        (hT : T ∈ Set.centralizer (Set.centralizer (A : Set (H →L[ℂ] H))))
        (hsa : IsSelfAdjoint T) (hnorm : ‖T‖ ≤ 1)
        (n : ℕ) (ξ : Fin n → H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a ∈ A, IsSelfAdjoint a ∧ ‖a‖ ≤ 1 ∧ ∀ i, ‖a (ξ i) - T (ξ i)‖ < ε := by
    …
  45. lemma OAI.TraceConeClassification.tuple_inner_inclusion line 277
  46. lemma OAI.TraceConeClassification.tuple_inclusion_inner line 284
  47. lemma OAI.TraceConeClassification.tuple_inclusion_norm line 288
  48. lemma OAI.TraceConeClassification.matrixEntry_star line 293
  49. lemma OAI.TraceConeClassification.matrixEntry_norm line 307
  50. lemma OAI.TraceConeClassification.matrixEntry_continuous line 317
  51. lemma OAI.TraceConeClassification.matrixEntry_zero line 323
  52. lemma OAI.TraceConeClassification.matrixEntry_add line 326
  53. lemma OAI.TraceConeClassification.matrixEntry_smul line 329
  54. lemma OAI.TraceConeClassification.matrixEntry_one line 332
  55. lemma OAI.TraceConeClassification.matrixEntry_mul line 338
  56. lemma OAI.TraceConeClassification.matrixEntry_diagonal line 345
  57. def OAI.TraceConeClassification.matrixSubalgebra line 350
  58. lemma OAI.TraceConeClassification.matrixSubalgebra_closed line 369
  59. lemma OAI.TraceConeClassification.diagonal_mem_matrixSubalgebra line 375
  60. lemma OAI.TraceConeClassification.diagonal_matrix_bicommutant line 381
  61. def OAI.TraceConeClassification.blockOp line 390
  62. lemma OAI.TraceConeClassification.blockOp_apply line 394
  63. lemma OAI.TraceConeClassification.blockOp_star line 398
  64. lemma OAI.TraceConeClassification.matrixEntry_blockOp line 411
  65. lemma OAI.TraceConeClassification.blockOp_mem_matrixSubalgebra line 419
  66. lemma OAI.TraceConeClassification.blockOp_eq_diagonal line 425
  67. def OAI.TraceConeClassification.offDiagonalOp line 431
  68. lemma OAI.TraceConeClassification.offDiagonal_selfadjoint line 434
  69. lemma OAI.TraceConeClassification.offDiagonal_apply_zero line 438
  70. lemma OAI.TraceConeClassification.offDiagonal_apply_one line 440
  71. lemma OAI.TraceConeClassification.offDiagonal_norm line 443
  72. lemma OAI.TraceConeClassification.offDiagonal_bicommutant line 456
  73. theorem OAI.TraceConeClassification.kaplansky_strong_star line 481

    Source documentation

    Contractive strong-star density obtained by self-adjoint matrix amplification.

    theorem kaplansky_strong_star
        (A : StarSubalgebra ℂ (H →L[ℂ] H)) (hclosed : IsClosed (A : Set (H →L[ℂ] H)))
        (T : H →L[ℂ] H)
        (hT : T ∈ Set.centralizer (Set.centralizer (A : Set (H →L[ℂ] H))))
        (hnorm : ‖T‖ ≤ 1) (n : ℕ) (ξ : Fin n → H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a ∈ A, ‖a‖ ≤ 1 ∧ ∀ i,
          ‖a (ξ i) - T (ξ i)‖ < ε ∧ ‖star a (ξ i) - star T (ξ i)‖ < ε := by
    …
  74. def OAI.TraceConeClassification.ofWOTHom line 507
  75. def OAI.TraceConeClassification.weakClosure line 515
  76. lemma OAI.TraceConeClassification.weakClosure_mem line 519
  77. lemma OAI.TraceConeClassification.weakClosure_closed line 523
  78. lemma OAI.TraceConeClassification.weakClosure_cfc line 527
  79. def OAI.TraceConeClassification.nonunitalSelfAdjointOrbit line 533
  80. lemma OAI.TraceConeClassification.weakClosure_selfadjoint_orthogonal line 539
  81. lemma OAI.TraceConeClassification.weakClosure_selfadjoint_strong_density line 574
  82. lemma OAI.TraceConeClassification.nonunital_kaplansky_selfadjoint line 605
  83. def OAI.TraceConeClassification.nonunitalMatrixSubalgebra line 633
  84. lemma OAI.TraceConeClassification.nonunitalMatrixSubalgebra_closed line 651
  85. lemma OAI.TraceConeClassification.diagonal_mem_nonunitalMatrixSubalgebra line 657
  86. lemma OAI.TraceConeClassification.blockOp_mem_nonunitalMatrixSubalgebra line 663
  87. lemma OAI.TraceConeClassification.blockOp_WOT_continuous line 670
  88. lemma OAI.TraceConeClassification.offDiagonal_WOT_continuous line 678
  89. lemma OAI.TraceConeClassification.offDiagonal_weakClosure line 685
  90. theorem OAI.TraceConeClassification.nonunital_kaplansky_strong_star line 697

    Source documentation

    Literal norm-bounded strong-star density in the weak operator closure, valid also for degenerate nonunital representations.

    theorem nonunital_kaplansky_strong_star
        (A : NonUnitalStarSubalgebra ℂ (H →L[ℂ] H))
        (hclosed : IsClosed (A : Set (H →L[ℂ] H))) (T : H →L[ℂ] H)
        (hT : ContinuousLinearMapWOT.ofCLM T ∈ closure
          (ContinuousLinearMapWOT.ofCLM '' (A : Set (H →L[ℂ] H))))
        (hnorm : ‖T‖ ≤ 1) (n : ℕ) (ξ : Fin n → H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a ∈ A, ‖a‖ ≤ 1 ∧ ∀ i,
          ‖a (ξ i) - T (ξ i)‖ < ε ∧ ‖star a (ξ i) - star T (ξ i)‖ < ε := by
    …
  91. lemma OAI.TraceConeClassification.matrixEntry_decomposition line 725
  92. lemma OAI.TraceConeClassification.matrix_weakClosure line 731
  93. theorem OAI.TraceConeClassification.nonunital_matrix_kaplansky line 746

    Source documentation

    Matrix-level version for approximating positive Choi square roots; every approximating entry remains in the fixed hereditary algebra.

    theorem nonunital_matrix_kaplansky
        (m : ℕ) (A : NonUnitalStarSubalgebra ℂ (H →L[ℂ] H))
        (hclosed : IsClosed (A : Set (H →L[ℂ] H)))
        (T : HilbertTuple m H →L[ℂ] HilbertTuple m H)
        (hT : ∀ i j, matrixEntry m T i j ∈ weakClosure A) (hnorm : ‖T‖ ≤ 1)
        (n : ℕ) (ξ : Fin n → HilbertTuple m H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a : HilbertTuple m H →L[ℂ] HilbertTuple m H,
          (∀ i j, matrixEntry m a i j ∈ A) ∧ ‖a‖ ≤ 1 ∧ ∀ i,
            ‖a (ξ i) - T (ξ i)‖ < ε ∧ ‖star a (ξ i) - star T (ξ i)‖ < ε :=
    …

    Mentions: OAI.TraceConeClassification.HilbertTuple, OAI.TraceConeClassification.matrixEntry, OAI.TraceConeClassification.weakClosure

  94. lemma OAI.TraceConeClassification.weakClosure_strong_star_density line 766

    Source documentation

    Strong-star approximation on finitely many vectors, without a norm bound on the approximants. No closed-range assumption is necessary.

    lemma weakClosure_strong_star_density (A : NonUnitalStarSubalgebra ℂ (H →L[ℂ] H))
        (T : H →L[ℂ] H) (hT : T ∈ weakClosure A)
        (n : ℕ) (ξ : Fin n → H) (ε : ℝ) (hε : 0 < ε) :
        ∃ a ∈ A, ∀ i, ‖a (ξ i)-T (ξ i)‖ < ε ∧ ‖star a (ξ i)-star T (ξ i)‖ < ε := by
    …

    Mentions: OAI.TraceConeClassification.weakClosure