Jtdylktuy

Let $X$ be a topological space and $Y$ be a metric space. Prove that the space of continuous functions $C(X, Y )$ with the topology of compact convergence is Hausdorff.

The compact convergence topology is generated by the collection of sets $B_C(f,ϵ)={g∈Y^X: text{sup }_{x∈C} d(f(x),g(x))<ϵ}$, with compact $C⊂X$.

I know to show a topology is Hausdorff we need to show that for any two distinct elements in the topology we can find neighborhoods of those elements that do not intersect, but I am not sure how to do this for the compact convergence topology. The functions and supremum are throwing me off.

Suppose $f neq g$. We know that there must be some $p in X$ with $f(p) neq g(p)$.
Define $varepsilon = frac{d(f(p),g(p))}{2} >0$, where $d$ is the metric on $Y$.

Now define $C={p}$, which is finite, so compact. A supremum of $d(f(x), g(x))$ with $x in C$ is then just the single value $d(f(p), g(p))$.

Then $f in B_C(f,varepsilon) = {h in Y^X: d(f(p), h(p)) < varepsilon}$ and $g in B_C(g,varepsilon) = {h in Y^X: d(g(p), h(p)) < varepsilon}$.

If $h in B_C(f, varepsilon) cap B(g, varepsilon)$ existed, then both

$$d(h(p), f(p)) < varepsilon text{, and } d(h(p), g(p)) < varepsilon$$

and so $$d(f(p), g(p)) le d(f(p), h(p)) + d(h(p), g(p)) < 2varepsilon = d(f(p), g(p)$$

which is a contradiction. So $B_C(f, varepsilon) cap B(g, varepsilon) = emptyset$ and $C(X,Y)$ is Hausdorff.

Hint: Singleton sets ${x}$ are always compact