Show that the discrete topology on X is induced by the metric

0 if x=y, 1 if x y

Is the trivial topology metrizable?

Printable View

- April 7th 2009, 12:35 PMAndreametMetric inducing Discrete Topology
Show that the discrete topology on X is induced by the metric

0 if x=y, 1 if x y

Is the trivial topology metrizable? - April 7th 2009, 01:01 PMPlato
- April 7th 2009, 02:11 PMAndreamet
- April 7th 2009, 02:55 PMPlato
- April 7th 2009, 03:30 PMAndreamet
Well,every set is open in the discrete topology. I am having trouble connecting the notion of distance to open sets in metrics. I know balls are probably the answer, but how do I build a ball from this metric? epsilon<1.001?

- April 7th 2009, 03:48 PMPlato
- April 7th 2009, 08:25 PMaliceinwonderland
A discrete topological space is metrizable. You can give each singleton set (an open ball whose radius with respect to the discrete metric d ) in X as a basis element.

You need to check whether singleton sets form a basis for a discrete topological space X.

(1) Check if singleton sets cover X.

(2) If two basis elements have an intersection, then for each x in the intersection, there is another basis element containing x and contained in the intersection.

For (2), if there is no intersection, (2) is vacuously true.

-----------------------------------------------------------

The trivial topological space is not metrizable, since it is not a Hausdorff space ( Metrizable spaces are always Hausdorff and paracompact).