https://www.carpathian.cunbm.utcluj.ro/article/on-pp-cluster-sets-and-their-application-to-pp-closedness/
On pp-cluster sets and their application to pp-closedness - Carpathian Journal of Mathematics
May 10, 2017 - In this paper, the study of a new type of cluster sets for functions and multifunctions between topological spaces has been initiated by use of preopen sets of...
journal of mathematicscluster setsapplicationclosednesscarpathian