OAI/Analysis/Nonexpansive/Main.lean

GitHub source file

4 declarations, 0 contain sorry, 0 declared as axioms

Fixed points in the original norm

The counterexample reduction constructs the actual normalized minimal data. The adaptive tree, finite switching witnesses and whole-ball branch argument then contradict those data. The public statements use the given norm on the original real Banach space, including the zero and nonseparable cases.

  1. theorem OAI.ReflexiveFixedPoints.hasNonexpansiveFixedPointProperty_of_canonicallyReflexive line 26

    Source documentation

    A real reflexive Banach space has the nonexpansive fixed point property in its given norm. Reflexivity is canonical continuous-bidual surjectivity.

    theorem hasNonexpansiveFixedPointProperty_of_canonicallyReflexive
        (hX : CanonicallyReflexive X) : HasNonexpansiveFixedPointProperty X := by
    …

    Mentions: OAI.ReflexiveFixedPoints.CanonicallyReflexive, OAI.ReflexiveFixedPoints.HasNonexpansiveFixedPointProperty

  2. theorem OAI.ReflexiveFixedPoints.exists_fixedPoint_of_canonicallyReflexive line 40

    Source documentation

    Every nonexpansive selfmap of a nonempty closed bounded convex set has an actual fixed point, with nonexpansiveness stated in the original norm.

    Distinct definitions of this name: ComparatorChallenges/ReflexiveFixedPoints.lean:21 (different declaration text). Qualify references as OAI.ReflexiveFixedPoints.exists_fixedPoint_of_canonicallyReflexive@path.

    theorem exists_fixedPoint_of_canonicallyReflexive
        (hX : CanonicallyReflexive X) (C : Set X)
        (hne : C.Nonempty) (hclosed : IsClosed C)
        (hbounded : Bornology.IsBounded C) (hconvex : Convex ℝ C)
        (F : C → C)
        (hF : ∀ a b : C, ‖(F a : X) - (F b : X)‖ ≤ ‖(a : X) - (b : X)‖) :
        ∃ a : C, F a = a :=
    …

    Mentions: OAI.ReflexiveFixedPoints.CanonicallyReflexive

  3. theorem OAI.ReflexiveFixedPoints.exists_fixedPoint_of_lipschitzWith_one line 51

    Source documentation

    The equivalent metric formulation has Lipschitz constant one.

    theorem exists_fixedPoint_of_lipschitzWith_one
        (hX : CanonicallyReflexive X) (C : Set X)
        (hne : C.Nonempty) (hclosed : IsClosed C)
        (hbounded : Bornology.IsBounded C) (hconvex : Convex ℝ C)
        (F : C → C) (hF : LipschitzWith 1 F) :
        ∃ a : C, F a = a :=
    …

    Mentions: OAI.ReflexiveFixedPoints.CanonicallyReflexive

  4. theorem OAI.ReflexiveFixedPoints.exists_ambient_fixedPoint_of_canonicallyReflexive line 62

    Source documentation

    The ambient-map formulation asserts membership and the literal equation for the original map.

    theorem exists_ambient_fixedPoint_of_canonicallyReflexive
        (hX : CanonicallyReflexive X) (C : Set X)
        (hne : C.Nonempty) (hclosed : IsClosed C)
        (hbounded : Bornology.IsBounded C) (hconvex : Convex ℝ C)
        (F : X → X) (hmap : Set.MapsTo F C C)
        (hF : ∀ a ∈ C, ∀ b ∈ C, ‖F a - F b‖ ≤ ‖a - b‖) :
        ∃ a ∈ C, F a = a :=
    …

    Mentions: OAI.ReflexiveFixedPoints.CanonicallyReflexive