OAI/GroupTheory/Thompson/BasicPartition.lean

GitHub source file

19 declarations, 0 contain sorry, 0 declared as axioms

Finite partitions into basic dyadic intervals

Closed cells cover the unit interval; their open interiors are disjoint. Restriction is the actual inverse image of the cell set under affine insertion.

  1. structure OAI.ThompsonNonamenability.BasicPartition line 21
  2. theorem OAI.ThompsonNonamenability.BasicPartition.ext line 30
  3. def OAI.ThompsonNonamenability.BasicPartition.cellCount line 36
  4. def OAI.ThompsonNonamenability.BasicPartition.Respects line 39

    Source documentation

    The interval is exactly covered by partition cells contained in it.

    def Respects (T : BasicPartition) (I : BasicInterval) : Prop :=
    …

    Mentions: OAI.ThompsonNonamenability.BasicPartition, OAI.ThompsonNonamenability.BasicInterval

  5. theorem OAI.ThompsonNonamenability.BasicPartition.cellCount_pos line 42
  6. theorem OAI.ThompsonNonamenability.BasicPartition.respects_of_mem line 46
  7. theorem OAI.ThompsonNonamenability.BasicPartition.interiors_overlap_of_mem_interior_mem_carrier line 51
  8. theorem OAI.ThompsonNonamenability.BasicPartition.eq_of_mem_interior_mem_carrier line 65

    Source documentation

    At an interior point, even membership in another closed cell forces equality.

    theorem eq_of_mem_interior_mem_carrier (T : BasicPartition)
        {I J : BasicInterval} (hI : I ∈ T.cells) (hJ : J ∈ T.cells)
        {x : ℝ} (hxI : x ∈ I.interior) (hxJ : x ∈ J.carrier) : I = J := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicPartition, OAI.ThompsonNonamenability.BasicInterval

  9. theorem OAI.ThompsonNonamenability.BasicPartition.respects_iff line 73

    Source documentation

    Equivalent geometric crossing condition, including the endpoint argument.

    theorem respects_iff (T : BasicPartition) (I : BasicInterval) :
        T.Respects I ↔ ∀ K ∈ T.cells,
          (K.interior ∩ I.interior).Nonempty → K.Contained I := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicPartition, OAI.ThompsonNonamenability.BasicInterval

  10. theorem OAI.ThompsonNonamenability.BasicPartition.respects_of_mesh_lt line 108

    Source documentation

    A sufficiently fine actual partition respects the specified basic interval.

    theorem respects_of_mesh_lt (T : BasicPartition) (I : BasicInterval)
        (hmesh : ∀ K ∈ T.cells, K.length < I.length) : T.Respects I := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicPartition, OAI.ThompsonNonamenability.BasicInterval

  11. def OAI.ThompsonNonamenability.BasicPartition.restrictCells line 120

    Source documentation

    Affinely normalized cells. Membership is exactly membership after insertion.

    def restrictCells (T : BasicPartition) (I : BasicInterval) : Finset BasicInterval :=
    …

    Mentions: OAI.ThompsonNonamenability.BasicPartition, OAI.ThompsonNonamenability.BasicInterval

  12. theorem OAI.ThompsonNonamenability.BasicPartition.mem_restrictCells line 124
  13. def OAI.ThompsonNonamenability.BasicPartition.restrict line 129

    Source documentation

    The genuine partition obtained by restriction and affine normalization.

    def restrict (T : BasicPartition) (I : BasicInterval) (h : T.Respects I) :
        BasicPartition where
    …

    Mentions: OAI.ThompsonNonamenability.BasicPartition, OAI.ThompsonNonamenability.BasicInterval

  14. theorem OAI.ThompsonNonamenability.BasicPartition.mem_restrict_cells line 153
  15. theorem OAI.ThompsonNonamenability.BasicPartition.restrict_proof_irrel line 158
  16. theorem OAI.ThompsonNonamenability.BasicPartition.restrict_cellCount_eq_filter_card line 162
  17. theorem OAI.ThompsonNonamenability.BasicPartition.restrict_cellCount_lt line 173
  18. theorem OAI.ThompsonNonamenability.BasicPartition.restrict_respects line 190
  19. theorem OAI.ThompsonNonamenability.BasicPartition.restrict_restrict line 207