OAI/GroupTheory/PolycyclicRecognition/Analysis/SequenceScaleExtraction.lean

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2 declarations, 0 contain sorry, 0 declared as axioms

Cofinal, strictly increasing scales with one fixed finite mode

  1. theorem OAI.PolycyclicRecognition.exists_strictMono_scale_subsequence line 14

    Source documentation

    A divergent real scale can be made strictly increasing and at least one by restricting the original sequence.

    theorem exists_strictMono_scale_subsequence (scale : ℕ → ℝ)
        (hs : Tendsto scale atTop atTop) :
        ∃ u : ℕ → ℕ, StrictMono u ∧ StrictMono (scale ∘ u) ∧
          ∀ n, 1 ≤ scale (u n) := by
    …
  2. theorem OAI.PolycyclicRecognition.exists_constant_mode_strict_scale line 32

    Source documentation

    Fix a finite mode first, then make the real scales strictly increasing. This applies in particular to the finite family of word-basis selections.

    theorem exists_constant_mode_strict_scale {I : Type*} [Finite I]
        (mode : ℕ → I) (scale : ℕ → ℝ) (hs : Tendsto scale atTop atTop) :
        ∃ (i : I) (u : ℕ → ℕ), StrictMono u ∧ StrictMono (scale ∘ u) ∧
          (∀ n, 1 ≤ scale (u n)) ∧ ∀ n, mode (u n) = i := by
    …