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On pre-\(\theta\)-open sets and two classes of functions. (English) Zbl 1152.54302

Summary: We introduce the notions of pro-\(\theta\)-derived, pre-\(\theta\)-border, pre-\(\theta\)-frontier and pre-\(\theta\)-exterior of a set and study some of their basic properties. We also introduce two classes of functions called \(\theta\)-preopen functions and \(\theta\)-precloscd functions. We obtain their characterizations, their basic properties and their relationships with other types of functions between topological spaces.

MSC:

54A05 Topological spaces and generalizations (closure spaces, etc.)
54C10 Special maps on topological spaces (open, closed, perfect, etc.)
54D10 Lower separation axioms (\(T_0\)–\(T_3\), etc.)
54C08 Weak and generalized continuity