التطبيقات المفتوحة (المغلقة) من النمط في الفضاء ثنائي التبولوجيا

Abstract

In  this research, we  defined a new type of open function, which are open

( closed ) functions, then we studied some of the  properties of these functions and the relationship with previously defind functions.

We also found a necessary and sufficient condition for the function  to be

  open( closed ) in bitopological space.