English

Projective $\pi$-character bounds the order of a $\pi$-base

General Topology 2007-05-23 v1

Abstract

All spaces below are Tychonov. We define the projective pi-character p(X) of a space X as the supremum of the values πχ(Y)\pi\chi(Y) where Y ranges over all continuous images of X. Our main result says that every space X has a pi-base whose order is at most p(X), that is every point in X is contained in at most p(X)-many members of the pi-base. Since p(X) is at most t(X) for compact X, this provides a significant generalization of a celebrated result of Shapirovskii.

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Cite

@article{arxiv.math/0703835,
  title  = {Projective $\pi$-character bounds the order of a $\pi$-base},
  author = {Istvan Juhasz and Zoltan Szentmiklossy},
  journal= {arXiv preprint arXiv:math/0703835},
  year   = {2007}
}

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7 pages