Changes

Normal space is a Hausdorff [[topological space]] in which, given any pair of disjoint closed sets E and F, there exist neighbourhoods U of E and V of F that are disjoint.  A product of normal spaces is not necessarily normal, the Sorgenfrey plane is an example of a product of normal spaces that is not normal.  On the other hand, every regular space with a countable basis is normal.

Normal space is a Hausdorff [[topological space]] in which, given any pair of disjoint closed sets E and F, there exist neighbourhoods U of E and V of F that are disjoint.  A product of normal spaces is not necessarily normal, the Sorgenfrey plane is an example of a product of normal spaces that is not normal.  On the other hand, every regular space with a countable basis is normal.

By the Urysohn lemma, any 2 disjoint, closed subsets of a normal space can be seperated by a contnous function.  The converse also hold.

By the Urysohn lemma, any 2 disjoint, closed subsets of a normal space can be seperated by a [[continous function]].  The converse also hold.

[[Category:Mathematics]]

[[Category:Mathematics]]