A tale of three hedgehogs
General Topology
2017-11-27 v1
Abstract
In this work we study three topologies defined over the same set: the hedgehog. As the name suggests, the hedgehog can be described as a set of spines identified at a single point. Among others, we give a proof of the Kowalsky hedgehog theorem, which asserts that every metrizable space is embeddable into a countable cartesian power of the metric hedgehog. Besides, the concept of collectionwise normality will characterized by means of a Tietze type extension theorem. In particular we give a proof of the fact that collectionwise normality is hereditary with respect to sets.
Cite
@article{arxiv.1711.08656,
title = {A tale of three hedgehogs},
author = {Igor Arrieta Torres},
journal= {arXiv preprint arXiv:1711.08656},
year = {2017}
}