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.
Citation
Lubica Holá. Alireza Kamel Mirmostafaee. Zbigniew Piotrowski. "Points of openness and closedness of some mappings." Banach J. Math. Anal. 9 (1) 243 - 252, 2015. https://doi.org/10.15352/bjma/09-1-18
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