Sn-networks、sq-spaces And Weakly Bisequential Spaces

In this paper, we mainly discuss the convergences or accumulate points in the topologicalspaces. It is composed by star operators, sq-spaces and weakly bisequential spaces. Firstly,we discusse the relations among star operators, sequential closure operators and closureoperators on sn-networks, and then we obtain the topology which is induced by some familyof subsets. Furthermore, we discuss this relationship between this topology and the originaltopology. Secondly, we discuss the condictions when a sequential closed set is a stronglysequential closed set; we define the sq-spaces and strongly sequentially quotient mappings;we study the properties and relations among the strongly sequentially quotient mappings andrelated mappings; we characterite the sq-spaces by the certain imaging of metrizable spaces.Finally, we prove that every set-sequence-covering mapping on weakly bisequential spaces isa weakly biquotient mapping.