English

A characterization of a local vector valued Bollob\'as theorem

Functional Analysis 2021-05-07 v1

Abstract

In this paper, we are interested in giving two characterizations for the so-called property {\bf L}o,o_{o,o}, a local vector valued Bollob\'as type theorem. We say that (X,Y)(X, Y) has this property whenever given \eps>0\eps > 0 and an operador T:XYT: X \rightarrow Y, there is η=η(\eps,T)\eta = \eta(\eps, T) such that if xx satisfies T(x)>1η\|T(x)\| > 1 - \eta, then there exists x0SXx_0 \in S_X such that x0xx_0 \approx x and TT itself attains its norm at x0x_0. This can be seen as a strong (although local) Bollob\'as theorem for operators. We prove that the pair (X,Y)(X, Y) has the {\bf L}o,o_{o,o} for compact operators if and only if so does (X,\K)(X, \K) for linear functionals. This generalizes at once some results due to D. Sain and J. Talponen. Moreover, we present a complete characterization for when (X\ptenY,\K)(X \pten Y, \K) satisfies the {\bf L}o,o_{o,o} for linear functionals under strict convexity or Kadec-Klee property assumptions in one of the spaces. As a consequence, we generalize some results in the literature related to the strongly subdifferentiability of the projective tensor product and show that (Lp(μ)×Lq(ν);\K)(L_p(\mu) \times L_q(\nu); \K) cannot satisfy the {\bf L}o,o_{o,o} for bilinear forms.

Cite

@article{arxiv.2105.02583,
  title  = {A characterization of a local vector valued Bollob\'as theorem},
  author = {Sheldon Dantas and Abraham Rueda Zoca},
  journal= {arXiv preprint arXiv:2105.02583},
  year   = {2021}
}

Comments

10 pages

R2 v1 2026-06-24T01:50:04.907Z