OAI/Analysis/Nonexpansive/Main.lean
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.
- theorem
OAI.ReflexiveFixedPoints.hasNonexpansiveFixedPointProperty_of_canonicallyReflexiveline 26Source 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
- theorem
OAI.ReflexiveFixedPoints.exists_fixedPoint_of_canonicallyReflexiveline 40Source 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 := … - theorem
OAI.ReflexiveFixedPoints.exists_fixedPoint_of_lipschitzWith_oneline 51Source 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 := … - theorem
OAI.ReflexiveFixedPoints.exists_ambient_fixedPoint_of_canonicallyReflexiveline 62Source 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 := …