This course will be an introduction to descriptive set theory, which is the study of definable sets in Polish spaces. We will develop the basic theory of the Borel and projective hierarchies in Polish spaces, with emphasis on regularity properties of the real line, including questions of measurability, category, cardinality, and determinacy. Our treatment will be classical, which means we will stop short of the point where effective techniques and forcing come into the picture, though we will not hesitate to state independence results and thereby confront the limits of what can be done in ZFC. The only prerequisites are familiarity with basic point-set topology and measure theory. |