229,417 research outputs found
Zero Error Coordination
In this paper, we consider a zero error coordination problem wherein the
nodes of a network exchange messages to be able to perfectly coordinate their
actions with the individual observations of each other. While previous works on
coordination commonly assume an asymptotically vanishing error, we assume
exact, zero error coordination. Furthermore, unlike previous works that employ
the empirical or strong notions of coordination, we define and use a notion of
set coordination. This notion of coordination bears similarities with the
empirical notion of coordination. We observe that set coordination, in its
special case of two nodes with a one-way communication link is equivalent with
the "Hide and Seek" source coding problem of McEliece and Posner. The Hide and
Seek problem has known intimate connections with graph entropy, rate distortion
theory, Renyi mutual information and even error exponents. Other special cases
of the set coordination problem relate to Witsenhausen's zero error rate and
the distributed computation problem. These connections motivate a better
understanding of set coordination, its connections with empirical coordination,
and its study in more general setups. This paper takes a first step in this
direction by proving new results for two node networks
Coordinated Path Following of UAVs over Time-Varying Digraphs Connected in an Integral Sense
This paper presents a new connectivity condition on the information flow
between UAVs to achieve coordinated path following. The information flow is
directional, so that the underlying communication network topology is
represented by a time-varying digraph. We assume that this digraph is connected
in an integral sense. This is a much more general assumption than the one
currently used in the literature. Under this assumption, it is shown that a
decentralized coordination controller ensures exponential convergence of the
coordination error vector to a neighborhood of zero. The efficacy of the
algorithm is confirmed with simulation results
Information Nonanticipative Rate Distortion Function and Its Applications
This paper investigates applications of nonanticipative Rate Distortion
Function (RDF) in a) zero-delay Joint Source-Channel Coding (JSCC) design based
on average and excess distortion probability, b) in bounding the Optimal
Performance Theoretically Attainable (OPTA) by noncausal and causal codes, and
computing the Rate Loss (RL) of zero-delay and causal codes with respect to
noncausal codes. These applications are described using two running examples,
the Binary Symmetric Markov Source with parameter p, (BSMS(p)) and the
multidimensional partially observed Gaussian-Markov source. For the
multidimensional Gaussian-Markov source with square error distortion, the
solution of the nonanticipative RDF is derived, its operational meaning using
JSCC design via a noisy coding theorem is shown by providing the optimal
encoding-decoding scheme over a vector Gaussian channel, and the RL of causal
and zero-delay codes with respect to noncausal codes is computed.
For the BSMS(p) with Hamming distortion, the solution of the nonanticipative
RDF is derived, the RL of causal codes with respect to noncausal codes is
computed, and an uncoded noisy coding theorem based on excess distortion
probability is shown. The information nonanticipative RDF is shown to be
equivalent to the nonanticipatory epsilon-entropy, which corresponds to the
classical RDF with an additional causality or nonanticipative condition imposed
on the optimal reproduction conditional distribution.Comment: 34 pages, 12 figures, part of this paper was accepted for publication
in IEEE International Symposium on Information Theory (ISIT), 2014 and in
book Coordination Control of Distributed Systems of series Lecture Notes in
Control and Information Sciences, 201
Coordinated Path Following of UAVs using Event-Triggered Communication over Time-Varying Networks with Digraph Topologies
In this article, a novel time-coordination algorithm based on event-triggered
communications is proposed to achieve coordinated path-following of UAVs. To be
specific, in the approach adopted a UAV transmits its progression information
over a time-varying network to its neighbors only when a decentralized trigger
condition is satisfied, thereby significantly reducing the volume of
inter-vehicle communications required when compared with the existing
algorithms based on continuous communications. Using such intermittent
communications, it is shown that a decentralized coordination controller
guarantees exponential convergence of the coordination error to a neighborhood
of zero. Also, a lower bound on the interval between two consecutive
event-triggered times is provided showing that the chattering issue does not
arise with the proposed algorithm. Finally, simulation results validate the
efficacy of the proposed algorithm.Comment: arXiv admin note: text overlap with arXiv:2307.0655
How to Coordinate Edge Devices for Over-the-Air Federated Learning?
This work studies the task of device coordination in wireless networks for
over-the-air federated learning (OTA-FL). For conventional metrics of
aggregation error, the task is shown to describe the zero-forcing (ZF) and
minimum mean squared error (MMSE) schemes and reduces to the NP-hard problem of
subset selection. We tackle this problem by studying properties of the optimal
scheme. Our analytical results reveal that this scheme is found by searching
among the leaves of a tree with favorable monotonic features. Invoking these
features, we develop a low-complexity algorithm that approximates the optimal
scheme by tracking a dominant path of the tree sequentially. Our numerical
investigations show that the proposed algorithm closely tracks the optimal
scheme
Coordination corrected ab initio formation enthalpies
The correct calculation of formation enthalpy is one of the enablers of ab-initio computational materials design. For several classes of systems (e.g. oxides) standard density functional theory produces incorrect values. Here we propose the “coordination corrected enthalpies” method (CCE), based on the number of nearest neighbor cation–anion bonds, and also capable of correcting relative stability of polymorphs. CCE uses calculations employing the Perdew, Burke and Ernzerhof (PBE), local density approximation (LDA) and strongly constrained and appropriately normed (SCAN) exchange correlation functionals, in conjunction with a quasiharmonic Debye model to treat zero-point vibrational and thermal effects. The benchmark, performed on binary and ternary oxides (halides), shows very accurate room temperature results for all functionals, with the smallest mean absolute error of 27(24) meV/atom obtained with SCAN. The zero-point vibrational and thermal contributions to the formation enthalpies are small and with different signs—largely canceling each other
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