OAI/GroupTheory/PolycyclicRecognition/Analysis/ConeOffsetPacking.lean

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The offset inequality from actual lifted cells and section volumes

The first-sheet quotient restriction and the second-sheet ideal restriction bound all lifted cells. The tile count and source count then cancel their template exponents, leaving the sign of the quotient trace.

  1. theorem OAI.PolycyclicRecognition.card_le_real_finite_cover line 22

    Source documentation

    The covering need not partition the endpoints, and empty tiles are allowed. A common real cardinal bound still sums over the finite cover.

    theorem card_le_real_finite_cover {G : Type*} {k : ℕ}
        (s : Finset G) (t : Fin k → Finset G)
        (hcover : ∀ x ∈ s, ∃ j, x ∈ t j) {B : ℝ}
        (hbound : ∀ j, ((t j).card : ℝ) ≤ B) :
        (s.card : ℝ) ≤ (k : ℝ) * B := by
    …
  2. theorem OAI.PolycyclicRecognition.cone_offset_nonpos_of_lifted_cells line 50

    Source documentation

    This is the geometric counting endgame: restrictions on actual quotient and ideal coordinates imply the offset trace inequality. No point-count estimate or offset-sign assertion is assumed.

    theorem cone_offset_nonpos_of_lifted_cells
        (π : N →* Q) (hπ : Continuous π) (σ : C(Q, N))
        (hs : ∀ q, π (σ q) = q)
        (μQ : Measure Q) (μI : Measure π.ker) (μ : Measure N) (ν : Measure D)
        [SFinite μQ] [SFinite μI] [SFinite μ] [SFinite ν]
        [μQ.IsMulLeftInvariant] [μ.IsMulLeftInvariant] [ν.IsMulLeftInvariant]
        (hμ : μ = Measure.map (quotientSectionHomeomorph π hπ σ hs).symm
          (μQ.prod μI))
        (φ : D →* MulAut N) (ι : N →* G) (κ : D →* G)
        (hc : ∀ d n, ι (φ d n) = κ d * ι n * (κ d)⁻¹)
        (hφ : ∀ d, MeasurePreserving (φ d) μ μ)
        (scale : ℕ → ℝ) (hscale : Tendsto scale atTop atTop)
    …

    Mentions: OAI.PolycyclicRecognition.quotientSectionHomeomorph