We compare three notions of genericity of separable metric structures. Our analysis provides a general model theoretic technique of showing that structures are generic in descriptive set theoretic (topological) sense and in measure theoretic sense. In particular, it gives a new perspective on Vershik’s theorems on genericity and randomness of Urysohn’s space among separable metric spaces.

The space of metric measure spaces (complete separable metric spaces with a probability measure) is becoming more and more important as state space for stochastic processes. Of particular interest is the subspace of (continuum) metric measure trees. Greven, Pfaffelhuber and Winter introduced the Gromov-Prohorov metric dGP on the space of metric measure spaces and showed that it induces the Grom...

We show that every locally compact Polish group is isomorphic to the isometry group of a proper separable metric space. This answers a question of Gao and Kechris. We also analyze the natural action of the isometry group of a separable ultrametric space on the space. This leads us to a structure theorem representing an arbitrary separable ultrametric space as a bundle with an ultrametric base a...

A Bayesian model is nonparametric if its parameter space has infinite dimension; typical choices are spaces of discrete measures and Hilbert spaces. We consider the construction of nonparametric priors when the parameter takes values in a more general functional space. We (i) give a Prokhorov-type representation result for nonparametric Bayesian models; (ii) show how certain tractability proper...

We prove that a space is a sequentially-quotient (pseudo-sequencecovering), π-image of a separable metric space if and only if it has a point-star network consisting of countable-cs∗-covers. We also investigate spaces with count-

We extend the theory of distance (Brownian) covariance from Euclidean spaces, where it was introduced by Székely, Rizzo and Bakirov, to general metric spaces. We show that for testing independence, it is necessary and sufficient that the metric space be of strong negative type. In particular, we show that this holds for separable Hilbert spaces, which answers a question of Kosorok. Instead of t...

We show that the space of all Lelek fans in a Cantor fan, equipped with the Hausdorff metric, is homeomorphic to the separable Hilbert space. This result is a special case of a general theorem we prove about spaces of upper semicontinuous functions on compact metric spaces that are strongly discontinuous.

We investigate properties of the class of compact spaces on which every regular Borel measure is separable. This class will be referred to as M S. We discuss some closure properties of M S, and show that some simply defined compact spaces, such as compact ordered spaces or compact scattered spaces, are in M S. Most of the basic theory for regular measures is true just in ZF C. On the other hand...

In this paper, we discuss the relationships between spaces with locally countable weak-bases and spaces with various locally countable networks, establish the relationships between spaces with locally countable weak-bases and locally separable metric spaces, and show that spaces have locally countable weak-bases if and only if they are locally Lindelöf, g-metrizable spaces. These are improvemen...