Alexandroff plank

Alexandroff plank in topology, an area of mathematics, is a topological space that serves as an instructive example.

The construction of the Alexandroff plank starts by defining the topological space

to be the Cartesian product of

is the first uncountable ordinal, and both carry the interval topology.

is extended to a topology

by adding the sets of the form

The Alexandroff plank is the topological space

It is called plank for being constructed from a subspace of the product of two spaces.

has the following properties: This topology-related article is a stub.

You can help Wikipedia by expanding it.