Plancherel formula for Berezin deformation of L2L^2 on Riemannian symmetric space

Consider the space B of complex $p\times q$ matrces with norm <1. There exists a standard one-parameter family $S_a$ of unitary representations of the pseudounitary group U(p,q) in the space of holomorphic functions on B (i.e. scalar highest weight representations). Consider the restriction $T_a$ of $S_a$ to the pseudoorthogonal group O(p,q). The representation of O(p,q) in $L^2$ on the symmetric space $O(p,q)/O(p)\times O(q)$ is a limit of the representations $T_a$ in some precise sence. Spectrum of a representation $T_a$ is comlicated and it depends on $\alpha$. We obtain the complete Plancherel formula for the representations $T_a$ for all admissible values of the parameter $\alpha$. We also extend this result to all classical noncompact and compact Riemannian symmetric spaces

Topological properties of concept spaces (full version)

AbstractBased on the observation that the category of concept spaces with the positive information topology is equivalent to the category of countably based T0 topological spaces, we investigate further connections between the learning in the limit model of inductive inference and topology. In particular, we show that the “texts” or “positive presentations” of concepts in inductive inference can be viewed as special cases of the “admissible representations” of computable analysis. We also show that several structural properties of concept spaces have well known topological equivalents. In addition to topological methods, we use algebraic closure operators to analyze the structure of concept spaces, and we show the connection between these two approaches. The goal of this paper is not only to introduce new perspectives to learning theorists, but also to present the field of inductive inference in a way more accessible to domain theorists and topologists

Domain Representable Spaces Defined by Strictly Positive Induction

Recursive domain equations have natural solutions. In particular there are domains defined by strictly positive induction. The class of countably based domains gives a computability theory for possibly non-countably based topological spaces. A $qcb_{0}$ space is a topological space characterized by its strong representability over domains. In this paper, we study strictly positive inductive definitions for $qcb_{0}$ spaces by means of domain representations, i.e. we show that there exists a canonical fixed point of every strictly positive operation on $qcb_{0}$ spaces.Comment: 48 pages. Accepted for publication in Logical Methods in Computer Scienc

Domain Representations Induced by Dyadic Subbases

We study domain representations induced by dyadic subbases and show that a proper dyadic subbase S of a second-countable regular space X induces an embedding of X in the set of minimal limit elements of a subdomain D of $\{0,1,\perp\}\omega$. In particular, if X is compact, then X is a retract of the set of limit elements of D

Spectral theory for non-unitary twists

Let $G$ be a Lie-group and \Ga\subset G a cocompact lattice. For a finite-dimensional, not necessarily unitary representation \om of \Ga we show that the $G$-representation on L^2(\Ga\bs G,\om) admits a complete filtration with irreducible quotients. As a consequence, we show the trace formula for non-unitary twists and arbitrary locally compact groups