A space is functionally countable if every real-valued continuous function has countable image. A stronger property recently defined by Tkachuk is exponential separability. We start by studying these properties in GO spaces, where we extend results by Tkachuk and Wilson, and prove a conjecture by Dow. We also study some subspaces of products that are functionally countable and the influence of the G delta - topology on exponential separability. Finally, we give some examples of functionally countable spaces that are separable and uncountable.

Comparing functional countability and exponential separability

Santi Spadaro
2025-01-01

Abstract

A space is functionally countable if every real-valued continuous function has countable image. A stronger property recently defined by Tkachuk is exponential separability. We start by studying these properties in GO spaces, where we extend results by Tkachuk and Wilson, and prove a conjecture by Dow. We also study some subspaces of products that are functionally countable and the influence of the G delta - topology on exponential separability. Finally, we give some examples of functionally countable spaces that are separable and uncountable.
2025
Functionally countable
Exponentially separable
Generalized ordered space
Souslin line
G delta - topology
Corson compactum
Eberlein compactum
Function space
Ostaszewski space
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11769/644374
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