İj-sets in bitopological space

In this thesis, it is defined the concept of pre intersection open set, pre union open set, semi intersection open set,semi union open set. By using these definition it has been defined pre intersection closure set, pre union closure set, semi intersection closure set, semi unıon closure set. Also, it has been defined the new closure sets such as ij union ji pre intersection closure, ij intersection\ ji pre intersection closure,\ ij union\ ji pre union closure, ij intersection ji\ pre union closure, ij union ji\ semi intersection closure, ij intersection ji semi intersection closure, ij union ji semi union closure,\ ij intersection ji semi union closure where i and j are the indices of topologies in the bitopological space. By using definitions of these closure sets,it is obtained definations of ij g closed set,\ ij g semi intersection closed set, ij g semi union closed set, ij semi intersection g closed set,\ ij semi union g closed set, ij g intersection closed set and ij g pre union closed set. In addition, the relations between these defined sets have been proven with theorems and supported with examples.