  This paper covers some recent progress in the study of sg-open sets,
sg-compact spaces, N-scattered spaces and some related concepts. A subset $A$
of a topological space $(X,\tau)$ is called sg-closed if the semi-closure of
$A$ is included in every semi-open superset of $A$. Complements of sg-closed
sets are called sg-open. A topological space $(X,\tau)$ is called sg-compact if
every cover of $X$ by sg-open sets has a finite subcover. N-scattered space is
a topological spaces in which every nowhere dense subset is scattered.
