# nLab frame of opens

### Context

#### Topology

topology

algebraic topology

## Examples

#### Topos Theory

Could not include topos theory - contents

Given a topological space $X$, the open subspaces of $X$ form a poset which is in fact a frame. This is the frame of open subspaces of $X$. When thought of as a locale, this is the topological locale $\Omega(X)$. When thought of as a category, this is the category of open subsets of $X$.

Similarly, given a locale $X$, the open subspaces of $X$ form a poset which is in fact a frame. This is the frame of open subspaces of $X$. When thought of as a locale, this is simply $X$ all over again. When thought of as a category, this is a site whose topos of sheaves is a localic topos.

The frame of open subsets of the point is given by the power set of a singleton, or more generally by the object of truth values of the ambient topos.

Revised on December 30, 2013 11:41:24 by Ingo Blechschmidt (46.244.180.181)