# Sorgenfrey Plane

The **Sorgenfrey Plane** is an example of a product space of two Lindelöf spaces that is not itself Lindelöf.^{[1]}

## Definition

The Sorgenfrey Plane, named after mathematician Robert Sorgenfrey, is defined as the product topology of two Lindelöf spaces, like so: $$\mathbb{R}_\ell \times \mathbb{R}_\ell = \mathbb{R}^2_\ell$$

## Further Reading

## External Links

## References

- ↑ Munkres, James R. Topology, 2015. pg. 191.