OAI/GroupTheory/Thompson/OrderedChainKnots.lean

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12 declarations, 0 contain sorry, 0 declared as axioms

Indexed knots of an ordered dyadic chain

An actual consecutive list of dyadic cells covering [0,1] gives a strictly increasing subdivision indexed by that same list. The two endpoints of its ith piece are exactly the endpoints of the ith listed cell.

  1. def OAI.ThompsonNonamenability.GapChain.realKnots line 23

    Source documentation

    The initial endpoint followed by the right endpoints of the cells.

    def realKnots : (a : ℝ) → (L : List BasicInterval) → Fin (L.length + 1) → ℝ
      | a, [], _ => a
      | a, I :: L, i => Fin.cases a (realKnots I.right L) i

    Mentions: OAI.ThompsonNonamenability.BasicInterval

  2. theorem OAI.ThompsonNonamenability.GapChain.realKnots_zero line 27
  3. theorem OAI.ThompsonNonamenability.GapChain.realKnots_succ line 32

    Source documentation

    The right knot of each indexed piece is its actual right endpoint.

    theorem realKnots_succ (a : ℝ) (L : List BasicInterval) (i : Fin L.length) :
        realKnots a L i.succ = (L.get i).right := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicInterval, OAI.ThompsonNonamenability.GapChain.realKnots

  4. theorem OAI.ThompsonNonamenability.GapChain.realKnots_castSucc line 44

    Source documentation

    The chain equalities identify each left knot with its listed cell.

    theorem realKnots_castSucc {a b : ℝ} {L : List BasicInterval}
        (h : GapChain a b L) (i : Fin L.length) :
        realKnots a L i.castSucc = (L.get i).left := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicInterval, OAI.ThompsonNonamenability.GapChain, OAI.ThompsonNonamenability.GapChain.realKnots

  5. theorem OAI.ThompsonNonamenability.GapChain.realKnots_last line 56
  6. theorem OAI.ThompsonNonamenability.GapChain.strictMono_realKnots line 64
  7. theorem OAI.ThompsonNonamenability.GapChain.length_pos line 71
  8. theorem OAI.ThompsonNonamenability.GapChain.realKnots_mem_unit line 77
  9. theorem OAI.ThompsonNonamenability.GapChain.isDyadic_realKnots line 85
  10. structure OAI.ThompsonNonamenability.ChainSubdivision line 96

    Source documentation

    A subdivision whose indexing agrees with an actual ordered cell list.

    structure ChainSubdivision (L : List BasicInterval) where
    …

    Mentions: OAI.ThompsonNonamenability.BasicInterval

  11. def OAI.ThompsonNonamenability.GapChain.toSubdivision line 111

    Source documentation

    Construct all subdivision data from the chain equalities.

    def toSubdivision {L : List BasicInterval} (h : GapChain 0 1 L) :
        ChainSubdivision L := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicInterval, OAI.ThompsonNonamenability.GapChain, OAI.ThompsonNonamenability.ChainSubdivision

  12. theorem OAI.ThompsonNonamenability.ChainSubdivision.mem_carrier_iff line 137

    Source documentation

    Membership in an indexed cell is exactly membership between its knots.

    theorem mem_carrier_iff {L : List BasicInterval} (s : ChainSubdivision L)
        (i : Fin L.length) (x : UnitInterval) :
        (x : ℝ) ∈ (L.get i).carrier ↔ s.knots i.castSucc ≤ x ∧ x ≤ s.knots i.succ := by
    …

    Mentions: OAI.ThompsonNonamenability.BasicInterval, OAI.ThompsonNonamenability.ChainSubdivision, OAI.ThompsonNonamenability.UnitInterval