## Banach Journal of Mathematical Analysis

### Points of openness and closedness of some mappings

#### Abstract

Let $X$ and $Y$ be topological spaces and $f : X \rightarrow Y$ be a continuous function. We are interested in finding points of $Y$ at which $f$ is open or closed. We will show that under certain conditions, the set of points of openness or closedness of $f$ in $Y$ , i.e. points of $Y$ at which $f$ is open (resp. closed) is a $G_{\delta}$ subset of $Y$. We will extend some results of S. Levi, R. Engelking and I. A. Vaĭnšteĭn.

#### Article information

Source
Banach J. Math. Anal., Volume 9, Number 1 (2015), 243-252.

Dates
First available in Project Euclid: 19 December 2014

Permanent link to this document
https://projecteuclid.org/euclid.bjma/1419000590

Digital Object Identifier
doi:10.15352/bjma/09-1-18

Mathematical Reviews number (MathSciNet)
MR3296098

Zentralblatt MATH identifier
1322.54010

#### Citation

Holá, Lubica; Kamel Mirmostafaee, Alireza; Piotrowski, Zbigniew. Points of openness and closedness of some mappings. Banach J. Math. Anal. 9 (2015), no. 1, 243--252. doi:10.15352/bjma/09-1-18. https://projecteuclid.org/euclid.bjma/1419000590