Polish space

Summary

A Polish space is a separable topological space whose topology comes from a complete metric. Examples are the real line, $\R^n$, the Cantor set, the Baire space and every separable Banach space. Polish spaces are the natural setting of descriptive set theory and of much of probability theory. The name honours the Polish topologists and logicians, such as Sierpiński and Kuratowski, who first studied these spaces in depth.