Some examples concerning $L\Sigma(\leq\omega)$ and metrizably fibered compacta

TL;DR

This paper investigates the properties of $L ext{} extSigma( extless ext{} extomega)$-spaces, providing counterexamples to open questions, refuting a conjecture, and analyzing the structure of certain compact spaces.

Contribution

It constructs a separable Rosenthal compactum not belonging to $L extSigma( extless ext{} extomega)$, and offers new insights into the structure of first-countable compacta.

Findings

Counterexamples to open questions about $L extSigma( extless ext{} extomega)$-spaces.

Refutation of a conjecture by Kubiś, Okunev, and Szeptycki.

Analysis of the structure of first-countable $(K)L extSigma( extless ext{} extomega)$-compacta.

Abstract

The class of $L\Sigma(\leq\omega)$-spaces was introduced in 2006 by Kubi\'s, Okunev and Szeptycki as a natural refinement of the classical and important notion of Lindel\"of $\Sigma$-spaces. Compact $L\Sigma(\leq\omega)$-spaces were considered earlier, under different names, in the works of Tkachuk and Tkachenko in relation to metrizably fibered compacta. In this paper we give counterexamples to several open questions about compact $L\Sigma(\leq\omega)$-spaces that are scattered in the literature. Among other things, we refute a conjecture of Kubi\'s, Okunev and Szeptycki by constructing a separable Rosenthal compactum which is not an $L\Sigma(\leq\omega)$-space. We also give insight to the structure of first-countable $(K)L\Sigma(\leq\omega)$-compacta.