The Set-Self-Tietze Property
General Topology
2026-03-17 v1
Abstract
We introduce the set-self-Tietze property, an analogue of the self-Tietze property for upper semi-continuous set-valued functions. A topological space is self-Tietze, if for every closed and continuous function , there is a continuous extension of . A topological space is set-self-Tietze, if for every closed and upper semi-continuous set-valued function , there exists an upper semi-continuous set-valued function such that . We show every compact metric space is set-self-Tietze, and that the torus is not self-Tietze.
Cite
@article{arxiv.2603.14404,
title = {The Set-Self-Tietze Property},
author = {Andrew Wood},
journal= {arXiv preprint arXiv:2603.14404},
year = {2026}
}