English

Retraction methods and fixed point free maps with null minimal displacements on unit balls

Functional Analysis 2024-09-04 v2

Abstract

In this paper we consider the class of Lipschitz maps on the unit ball BXB_X of a Banach space XX, and the question we deal with is whether for any λ>1\lambda>1 there exists a λ\lambda-Lipschitz fixed-point free mapping T ⁣:BXBXT\colon B_X\to B_X with d(T,BX)=0\mathrm{d}(T,B_X)=0. We also consider its H\"older version. New related results are obtained. We show that if XX has a spreading Schauder basis then such mappings can always be built, answering a question posed by the first author in \cite{Bar}. In the general case, using a recent approach of R. Medina \cite{M} concerning H\"older retractions of (rn)(r_n)-flat closed convex sets, we show that for any decreasing null sequence (rn)R(r_n)\subset \mathbb{R} and α(0,1)\alpha\in (0,1), there exists a fixed-point free mapping TT on BXB_X so that TnxTnyrn(xyα+1)\|T^nx - T^n y\|\leq r_n(\| x - y\|^\alpha +1) for all x,yBXx, y\in B_X and nNn\in\mathbb{N}.

Keywords

Cite

@article{arxiv.2307.12958,
  title  = {Retraction methods and fixed point free maps with null minimal displacements on unit balls},
  author = {C. S. Barroso and V. Ferreira},
  journal= {arXiv preprint arXiv:2307.12958},
  year   = {2024}
}

Comments

Comments welcome

R2 v1 2026-06-28T11:38:53.106Z