# Math Help - topology on three point set?

1. ## topology on three point set?

Let X = {a,b,c}
Construct a topology on X so that there is a compact set that is not closed.

2. Originally Posted by iamthemanyes
Let X = {a,b,c}
Construct a topology on X so that there is a compact set that is not closed.
Just make any topology where there is a non-closed set and that non-closed set will be compact since the set if sfinite.

3. Would this be an example:
{Zero set, X, {a}, {b,c}, {c}, {a,c}}

Then {c} is compact, but NOT closed?

4. Originally Posted by iamthemanyes
Would this be an example:
{Zero set, X, {a}, {b,c}, {c}, {a,c}}

Then {c} is compact, but NOT closed?
Right.