Lindelöf Indestructibility, Topological Games and Selection Principles

Marion Scheepers, Boise State University
Franklin D. Tall, University of Toronto

Abstract

Arhangel'skii proved that if a first countable Hausdorff space is Lindelöf, then its cardinality is at most 2 ^א‎0. Such a clean upper bound for Lindelöf spaces in the larger class of spaces whose points are G_δ has been more elusive. In this paper we continue the agenda started by the second author, [Topology Appl. 63 (1995)], of considering the cardinality problem for spaces satisfying stronger versions of the Lindelöf property. Infinite games and selection principles, especially the Rothberger property, are essential tools in our investigations.