Category Archives: Definition

Vietoris topology and Hausdorff metric

From Kechris: Let be a topological space.  We denote by the space of all compact subsets of equipped with the Vietoris topology. Let be a metric space with .  We define the Hausdorff metric on , , as follows: , … Continue reading

Posted in Analysis, Definition, Descriptive Set Theory, Kechris, Topology | Leave a comment


Definitions and notation for trees. .  If , and , .  If , the concatenation of and is defined by .  If , , then is an initial segment of and is an extension of (written ), if , for … Continue reading

Posted in Definition, Descriptive Set Theory, Kechris | Leave a comment