| Version 3 |
Version 2 |
| If $(X,\tau)$ is an arbitrary topological space and $A\subseteq X$ |
If $(X,\tau)$ is an arbitrary topological space and $A\subseteq X$ |
| then the union of all open sets contained in $A$ is defined to be |
then the union of all open sets contained in $A$ is defined to be |
| the interior of $A$. Equivalently, one could define the interior |
the interior of $A$. Equivalently, one could define the interior |
| of $A$ to the be the largest open set contained in $A$. We denoted |
of $A$ to the be the largest open set contained in $A$. We denoted |
| $\operatorname{int}(A)$ is one of the derived sets of a |
$\operatorname{int}(A)$ is one of the derived sets of a |
| topological space, others include boundary, closure etc. |
topological space, others include boundary, closure etc. |
