Explicit models of $\ell_1$-preduals and the weak$^*$ fixed point property in $\ell_1$

TL;DR

This paper characterizes preduals of  with finitely many weak*-limit points of the basis and constructs an -predual where the dual lacks the weak* fixed point property, answering an open question.

Contribution

It provides a concrete isometric description of certain  preduals and constructs an example addressing an open problem about the weak* fixed point property.

Findings

Characterizes preduals of  with finitely many weak*-limit points.

Constructs an -predual with dual lacking the weak* fixed point property.

Answers an open question from 2017 about the weak* fixed point property.

Abstract

We provide a concrete isometric description of all the preduals of $\ell_1$ for which the standard basis in $\ell_1$ has a finite number of $w^*$-limit points. Then, we apply this result to give an example of an $\ell_1$-predual $X$ such that its dual $X^*$ lacks the weak$^*$ fixed point property for nonexpansive mappings (briefly, $w^*$-FPP), but $X$ does not contain an isometric copy of any hyperplane $W_{\alpha}$ of the space $c$ of convergent sequences such that $W_\alpha$ is a predual of $\ell_1$ and $W_\alpha^*$ lacks the $w^*$-FPP. This answers a question left open in the 2017 paper of the present authors.