] In
topology, a branch of
mathematics concerning the study of shapes and
spaces, a
point x of a
topological space X is called an
isolated point of a subset
S of
X if
x belongs to
S and there exists in
X a
neighborhood of
x not containing other points of
S. This is equivalent to saying that the singleton {
x} is an open set in the topological space
S (considered as a
subspace of
X).