TITLE: Are two compact Hausdorff spaces homeomorphic if their algebras of continuous functions are isomorphic?
QUESTION [5 upvotes]: Suppose that $X$ and $Y$ are two compact Hausdorff spaces and $F\colon C(X) → C(Y)$ is a continuous isomorphism of algebras. Can I say $X$ and $Y$ are homeomorphic?
The key words always lead me to other questions. Can anyone give me some reference? Thanks a lot!

REPLY [6 votes]: This is the so-called Gelfand-Kolmogorov theorem. It says:

Let $X$ and $Y$ be compact, Hausdorff spaces. Suppose that there exists a ring isomorphism $T\colon C(X)\to C(Y)$. Then there exists a homeomorphism $h\colon Y\to X$ such that $$Tf = f\circ h\text{ for all }f\in C(X).$$ In particular, $T$ is a continuous algebra isomorphism.

Click here for some references. Actually there is a more general result due to Milgram which asserts that two compact Hausdorff spaces $X$ and $Y$ are homeomorphic if and only if there exists a multiplicative bijection between $C(X)$ and $C(Y)$.