54,770 research outputs found
Discrete isometry groups of symmetric spaces
This survey is based on a series of lectures that we gave at MSRI in Spring
2015 and on a series of papers, mostly written jointly with Joan Porti. Our
goal here is to:
1. Describe a class of discrete subgroups of higher rank
semisimple Lie groups, which exhibit some "rank 1 behavior".
2. Give different characterizations of the subclass of Anosov subgroups,
which generalize convex-cocompact subgroups of rank 1 Lie groups, in terms of
various equivalent dynamical and geometric properties (such as asymptotically
embedded, RCA, Morse, URU).
3. Discuss the topological dynamics of discrete subgroups on flag
manifolds associated to and Finsler compactifications of associated
symmetric spaces . Find domains of proper discontinuity and use them to
construct natural bordifications and compactifications of the locally symmetric
spaces .Comment: 77 page
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 space is a topological space characterized by
its strong representability over domains. In this paper, we study strictly
positive inductive definitions for spaces by means of domain
representations, i.e. we show that there exists a canonical fixed point of
every strictly positive operation on spaces.Comment: 48 pages. Accepted for publication in Logical Methods in Computer
Scienc
On the irreducibility of locally analytic principal series representations
Let G be a p-adic connected reductive group with Lie algebra g. For a
parabolic subgroup P in G and a finite-dimensional locally analytic
representation V of P, we study the induced locally analytic G-representation W
= Ind^G_P(V). Our result is the following criterion concerning the topological
irreducibility of W: if the Verma module U(g) \otimes_{U(p)} V' associated to
the dual representation V' is irreducible then W is topologically irreducible
as well.Comment: 44 pages; final version. An appendix has been added in which it is
shown that the canonical maps between certain completions of distribution
algebras are injective. This fills a gap in a previous version; it was
pointed out to us by a refere
Local rigidity of complex hyperbolic lattices in semisimple Lie groups
We show the local rigidity of complex hyperbolic lattices in classical
Hermitian semisimple Lie groups, . This reproves or generalizes some results in \cite{GM, KKP,
Klingler-inv, Pozzetti}.Comment: 14 pages, updated to give more explanation
Stochastic collocation on unstructured multivariate meshes
Collocation has become a standard tool for approximation of parameterized
systems in the uncertainty quantification (UQ) community. Techniques for
least-squares regularization, compressive sampling recovery, and interpolatory
reconstruction are becoming standard tools used in a variety of applications.
Selection of a collocation mesh is frequently a challenge, but methods that
construct geometrically "unstructured" collocation meshes have shown great
potential due to attractive theoretical properties and direct, simple
generation and implementation. We investigate properties of these meshes,
presenting stability and accuracy results that can be used as guides for
generating stochastic collocation grids in multiple dimensions.Comment: 29 pages, 6 figure
Computable de Finetti measures
We prove a computable version of de Finetti's theorem on exchangeable
sequences of real random variables. As a consequence, exchangeable stochastic
processes expressed in probabilistic functional programming languages can be
automatically rewritten as procedures that do not modify non-local state. Along
the way, we prove that a distribution on the unit interval is computable if and
only if its moments are uniformly computable.Comment: 32 pages. Final journal version; expanded somewhat, with minor
corrections. To appear in Annals of Pure and Applied Logic. Extended abstract
appeared in Proceedings of CiE '09, LNCS 5635, pp. 218-23
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