
doi: 10.4064/dm762-4-2018
arXiv: 1607.07978
Given a partially ordered set $P$ we study properties of topological spaces $X$ admitting a $P$-base, i.e., an indexed family $(U_\alpha)_{\alpha\in P}$ of subsets of $X\times X$ such that $U_\beta\subset U_\alpha$ for all $\alpha\le\beta$ in $P$ and for every $x\in X$ the family $(U_\alpha[x])_{\alpha\in P}$ of balls $U_\alpha[x]=\{y\in X:(x,y)\in U_\alpha\}$ is a neighborhood base at $x$. A $P$-base $(U_\alpha)_{\alpha\in P}$ for $X$ is called locally uniform if the family of entourages $(U_\alpha U_\alpha^{-1}U_\alpha)_{\alpha\in P}$ remains a $P$-base for $X$. A topological space is first-countable if and only if it has an $\omega$-base. By Moore's Metrization Theorem, a topological space is metrizable if and only if it is a $T_0$-space with a locally uniform $\omega$-base. In the paper we shall study topological spaces possessing a (locally uniform) $\omega^\omega$-base. Our results show that spaces with an $\omega^\omega$-base share some common properties with first countable spaces, in particular, many known upper bounds on the cardinality of first-countable spaces remain true for countably tight $\omega^\omega$-based topological spaces. On the other hand, topological spaces with a locally uniform $\omega^\omega$-base have many properties, typical for generalized metric spaces. Also we study Tychonoff spaces whose universal (pre- or quasi-) uniformity has an $\omega^\omega$-base and show that such spaces are close to being $\sigma$-compact.
Comment: 105 pages
\(\omega^\omega\)-dominance, preuniform space, quasiuniform space, 54D70, 54E15, 54E18, 54E35 (Primary), 03E04, 03E17, 54A20, 54A25, 54A35, 54C35, 54D15, 54D45, 54D65, 54G10, 54G20 (Secondary), Base properties of topological spaces, Mathematics - Logic, netbase, \(p\)-spaces, \(M\)-spaces, \(\sigma\)-spaces, etc., \(\omega^\omega\)-base, uniform space, Uniform structures and generalizations, Metric spaces, metrizability, network, generalized metric space, Mathematics - General Topology
\(\omega^\omega\)-dominance, preuniform space, quasiuniform space, 54D70, 54E15, 54E18, 54E35 (Primary), 03E04, 03E17, 54A20, 54A25, 54A35, 54C35, 54D15, 54D45, 54D65, 54G10, 54G20 (Secondary), Base properties of topological spaces, Mathematics - Logic, netbase, \(p\)-spaces, \(M\)-spaces, \(\sigma\)-spaces, etc., \(\omega^\omega\)-base, uniform space, Uniform structures and generalizations, Metric spaces, metrizability, network, generalized metric space, Mathematics - General Topology
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