Function space topologies are investigated for the class of continuous multifunctions. Using the notion of continuous convergence, splittingness and admissibility are discussed for the topologies on continuous multifunctions. The theory of net of sets is further developed for this purpose. The (τ, µ)-topology on the class of continuous multifunctions is found to be upper admissible, while the compact-open topology is upper splitting. The point-open topology is the coarsest topology which is coordinately admissible, it is also the finest topology which is coordinately splitting.2010 MSC: 54C35; 54A05; 54C60.

Extremal disconnectedness is further investigated for generalized topological spaces. It is found that extremally disconnected generalized topological spaces are a rich source of generalized lower semi-continuous and generalized upper semi-continuous mappings.

Pairwise extremally disconnected bitopological spaces exhibit properties similar to those of pairwise normal bitopological spaces. Due to this fact, we get results which resemble Uryshon's Lemma and Tietze's Extension Theorem for the pairwise extremally disconnected bitopological spaces.

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We define and study a new class of regular sets calledPS-regular sets. Properties of these sets are investigated for topological spaces and generalized topological spaces. Decompositions of regular open sets and regular closed sets are provided usingPS-regular sets. Semiconnectedness is characterized by usingPS-regular sets.PS-continuity and almostPS-continuity are introduced and investigated.