English

The fixed point property in direct sums and modulus R(a,X)

Functional Analysis 2015-11-24 v1

Abstract

We show that the direct sum of Banach spaces X1,...,XrX_{1},..., X_{r} with a strictly monotone norm has the weak fixed point property for nonexpansive mappings whenever M(Xi)>1M(X_{i})>1 for each i=1,...,ri=1,...,r. In particular, (X1...Xr)ψ(X_{1} \oplus ... \oplus X_{r})_{\psi} enjoys the fixed point property if Banach spaces XiX_{i} are uniformly nonsquare. This combined with the earlier results gives a definitive answer for r=2: the direct sum of uniformly nonsquare spaces X1,X2X_{1}, X_{2} with any monotone norm has FPP. Our results are extended for asymptotically nonexpansive mappings in the intermediate sense.

Keywords

Cite

@article{arxiv.1210.7823,
  title  = {The fixed point property in direct sums and modulus R(a,X)},
  author = {Andrzej Wiśnicki},
  journal= {arXiv preprint arXiv:1210.7823},
  year   = {2015}
}

Comments

12 pages

R2 v1 2026-06-21T22:29:39.950Z