English

Infinite games and cardinal properties of topological spaces

General Topology 2013-02-22 v2

Abstract

Inspired by work of Scheepers and Tall, we use properties defined by topological games to provide bounds for the cardinality of topological spaces. We obtain a partial answer to an old question of Bell, Ginsburg and Woods regarding the cardinality of weakly Lindel\"of first-countable regular spaces and answer a question recently asked by Babinkostova, Pansera and Scheepers. In the second part of the paper we study a game-theoretic version of cellularity, a special case of which has been introduced by Aurichi. We obtain a game-theoretic proof of Shapirovskii's bound for the number of regular open sets in an (almost) regular space and give a partial answer to a natural question about the productivity of a game strengthening of the countable chain condition that was introduced by Aurichi. As a final application of our results we prove that the Hajnal-Juh\'asz bound for the cardinality of a first-countable ccc Hausdorff space is true for almost regular (non-Hausdorff) spaces.

Keywords

Cite

@article{arxiv.1212.5724,
  title  = {Infinite games and cardinal properties of topological spaces},
  author = {Angelo Bella and Santi Spadaro},
  journal= {arXiv preprint arXiv:1212.5724},
  year   = {2013}
}

Comments

Corrected an error in the proof of Theorem 3.6