Category:Definitions/Open Sets

This category contains definitions related to open sets in the context of topology.
Related results can be found in Category:Open Sets.

Let $T = \struct {S, \tau}$ be a topological space.

Then the elements of $\tau$ are called the open sets of $T$.

Thus:

$U \in \tau$

and:

$U$ is open in $T$

are equivalent statements.