English

Weak$^*$-weak points of continuity on the state spaces

Functional Analysis 2026-04-17 v2

Abstract

Let XX be a Banach space. For xXx \in X with x=1\|x\| = 1, we denote the state space by Sx={xX:x=x(x)=1}.S_x = \{x^* \in X^* : \|x^*\| = x^*(x) = 1\}. In this paper, we study weak^*-weak and weak^*-\|\cdot\| points of continuity of the identity map on the state spaces in the space p(X)\ell^p(X) for 1<p<1 < p < \infty, where XX is a non-reflexive Banach space. We then use these results to characterize the weak and norm compactness of the state spaces of unit vectors in p(X)\ell^p(X). In addition, we address an open problem concerning the characterization of weakly compact state spaces in the space of Bochner-integrable functions L1(μ,X)L^1(\mu, X). We also provide a local solution to this problem without any additional assumptions on the Banach space XX. Motivated by the work of S. Daptari, V. Montesinos, and T. S. S. R. K. Rao, we show that if the set of all weak^*-weak points of continuity of L1(μ,X)1L^1(\mu, X)_1^* is weakly dense in L1(μ,X)1L^1(\mu, X)_1^*, then XX^* has the Radon-Nikod\'ym property (RNP).

Keywords

Cite

@article{arxiv.2604.08732,
  title  = {Weak$^*$-weak points of continuity on the state spaces},
  author = {Saurabh Dwivedi},
  journal= {arXiv preprint arXiv:2604.08732},
  year   = {2026}
}

Comments

This paper has been accepted for publication in Revista de la Real Academia de Ciencias Exactas, F\'isicas y Naturales. Serie A. Matem\'atica

R2 v1 2026-07-01T12:02:03.046Z