  Molodstov[10] introduced soft set theory as a new mathematical approach for
solving problems having uncertainties. Many researchers worked on the findings
of structures of soft set theory and applied to many problems having
uncertainties. Recently, Bin Chen [3-4] introduced and explored the properties
of soft semi-open sets and soft-semi-closed sets in soft topological spaces. In
this paper we continue to investigate the properties of soft semi-open and soft
semi-closed sets in soft topological spaces. We define soft semi-exterior, soft
semi-boundary, soft semi-open neighbourhood and soft semi-open neighbourhood
systems in soft topological spaces. Moreover we discuss the characterizations
and properties of soft semi-interior, soft semi-exterior, soft semi-closure and
soft semi-boundary. We also develop the relationship between soft semi-clopen
sets and soft semi-boundary. The addition of this topic in literature will
strengthen the theoretical base for further applications of soft topology in
decision analysis and information systems.
