Lindelof space

Definition
A topological space is said to be Lindelof if every open cover of it has a countable subcover.

Stronger properties

 * Compact space

Metaproperties
The product of two Lindelof spaces need not be a Lindelof space. A counterexample is the Sorgenfrey plane, which is a product of two copies of the Sorgenfrey line.

Textbook references

 * , Page 192 (definition in paragraph)