OAI/Analysis/Nonexpansive/ScalarNormalization.lean

GitHub source file

10 declarations, 0 contain sorry, 0 declared as axioms

Scalar normalization in the original norm

We move the actual invariant set by a positive scalar and conjugate its map. No norm instance is replaced. Minimality and absence of fixed points are transported by the explicit inverse scalar multiplication.

  1. def OAI.ReflexiveFixedPoints.scaledSubtypeEquiv line 26

    Source documentation

    The actual homothety between a set and its nonzero scalar image.

    def scaledSubtypeEquiv (K : Set X) (c : ℝ) (hc : c ≠ 0) : K ≃ (c • K : Set X) where
    …
  2. theorem OAI.ReflexiveFixedPoints.scaledSubtypeEquiv_apply line 35
  3. theorem OAI.ReflexiveFixedPoints.scaledSubtypeEquiv_symm_apply line 38
  4. def OAI.ReflexiveFixedPoints.scaledMap line 43

    Source documentation

    Conjugate an actual selfmap by the scalar bijection.

    def scaledMap (K : Set X) (T : K → K) (c : ℝ) (hc : c ≠ 0) :
        (c • K : Set X) → (c • K : Set X) :=
    …
  5. theorem OAI.ReflexiveFixedPoints.scaledMap_fixed_iff line 48

    Source documentation

    Fixed points pull back through the actual scalar change of variables.

    theorem scaledMap_fixed_iff (K : Set X) (T : K → K) (c : ℝ) (hc : c ≠ 0)
        (y : (c • K : Set X)) :
        scaledMap K T c hc y = y ↔
          T ((scaledSubtypeEquiv K c hc).symm y) = (scaledSubtypeEquiv K c hc).symm y := by
    …

    Mentions: OAI.ReflexiveFixedPoints.scaledMap, OAI.ReflexiveFixedPoints.scaledSubtypeEquiv

  6. theorem OAI.ReflexiveFixedPoints.scaledMap_nonexpansive line 61

    Source documentation

    Conjugation by a positive homothety preserves nonexpansiveness.

    theorem scaledMap_nonexpansive (K : Set X) (T : K → K)
        (hT : LipschitzWith 1 T) (c : ℝ) (hc : 0 < c) :
        LipschitzWith 1 (scaledMap K T c hc.ne') := by
    …

    Mentions: OAI.ReflexiveFixedPoints.scaledMap

  7. theorem OAI.ReflexiveFixedPoints.scaledMap_minimal line 85

    Source documentation

    The image under a positive homothety retains minimality.

    theorem scaledMap_minimal (K : Set X) (T : K → K)
        (hT : MinimalInvariant K T) (c : ℝ) (hc : 0 < c) :
        MinimalInvariant (c • K) (scaledMap K T c hc.ne') := by
    …

    Mentions: OAI.ReflexiveFixedPoints.MinimalInvariant, OAI.ReflexiveFixedPoints.scaledMap

  8. theorem OAI.ReflexiveFixedPoints.MinimalInvariantData.diam_pos line 117

    Source documentation

    A fixed-point-free invariant set cannot have zero diameter.

    theorem diam_pos (D : MinimalInvariantData (X := X)) : 0 < Metric.diam D.K := by
    …

    Mentions: OAI.ReflexiveFixedPoints.MinimalInvariantData

  9. def OAI.ReflexiveFixedPoints.MinimalInvariantData.scaled line 124

    Source documentation

    All structural properties survive the actual scalar homothety.

    def scaled (D : MinimalInvariantData (X := X)) (hX : CanonicallyReflexive X)
    …

    Mentions: OAI.ReflexiveFixedPoints.MinimalInvariantData, OAI.ReflexiveFixedPoints.CanonicallyReflexive

  10. theorem OAI.ReflexiveFixedPoints.MinimalInvariantData.scaled_inv_diam line 140

    Source documentation

    Diameter is exactly one after inverse-diameter scaling.

    theorem scaled_inv_diam (D : MinimalInvariantData (X := X))
    …

    Mentions: OAI.ReflexiveFixedPoints.MinimalInvariantData