6,206 research outputs found
Non Parametric Distributed Inference in Sensor Networks Using Box Particles Messages
This paper deals with the problem of inference in distributed systems where the probability model is stored in a distributed fashion. Graphical models provide powerful tools for modeling this kind of problems. Inspired by the box particle filter which combines interval analysis with particle filtering to solve temporal inference problems, this paper introduces a belief propagation-like message-passing algorithm that uses bounded error methods to solve the inference problem defined on an arbitrary graphical model. We show the theoretic derivation of the novel algorithm and we test its performance on the problem of calibration in wireless sensor networks. That is the positioning of a number of randomly deployed sensors, according to some reference defined by a set of anchor nodes for which the positions are known a priori. The new algorithm, while achieving a better or similar performance, offers impressive reduction of the information circulating in the network and the needed computation times
Asymptotic Flatness, Little String Theory, and Holography
We argue that any non-gravitational holographic dual to asymptotically flat
string theory in -dimensions naturally resides at spacelike infinity. Since
spacelike infinity can be resovled as a -dimensional timelike
hyperboloid (i.e., as a copy of de Sitter space in dimensions), the
dual theory is defined on a Lorentz signature spacetime. Conceptual issues
regarding such a duality are clarified by comparison with linear dilaton
boundary conditions, such as those dual to little string theory. We compute
both time-ordered and Wightman boundary 2-point functions of operators dual to
massive scalar fields in the asymptotically flat bulk.Comment: 27 pages, 2 figures. Explicit discussion added of using the Wightman
function method to calculate time-ordered boundary 2-point functions. The
resulting branch cuts are linked to the bulk spectrum of state
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