It doesn't make sense to say that "any point in a topology is open". "Open" is a property of sets of points, not individual points. Did you mean to say that "singleton sets", sets containing a single point?
Hi there
If I can prove that any point in a topology is open (for example the Sorgenfrey line) then it logically follows that the topological space concerned is T4 am I right?
Are there other usual ways to show whether a topological space is T4?
Regards