896 research outputs found
Lossy Compression with Near-uniform Encoder Outputs
It is well known that lossless compression of a discrete memoryless source
with near-uniform encoder output is possible at a rate above its entropy if and
only if the encoder is randomized. This work focuses on deriving conditions for
near-uniform encoder output(s) in the Wyner-Ziv and the distributed lossy
compression problems. We show that in the Wyner-Ziv problem, near-uniform
encoder output and operation close to the WZ-rate limit is simultaneously
possible, whereas in the distributed lossy compression problem, jointly
near-uniform outputs is achievable in the interior of the distributed lossy
compression rate region if the sources share non-trivial G\'{a}cs-K\"{o}rner
common information.Comment: Submitted to the 2016 IEEE International Symposium on Information
Theory (11 Pages, 3 Figures
Strong Coordination over Multi-hop Line Networks
We analyze the problem of strong coordination over a multi-hop line network
in which the node initiating the coordination is a terminal network node. We
assume that each node has access to a certain amount of randomness that is
local to the node, and that the nodes share some common randomness, which are
used together with explicit hop-by-hop communication to achieve strong
coordination. We derive the trade-offs among the required rates of
communication on the network links, the rates of local randomness available to
network nodes, and the rate of common randomness to realize strong
coordination. We present an achievable coding scheme built using multiple
layers of channel resolvability codes, and establish several settings in which
this scheme is proven to offer the best possible trade-offs.Comment: 35 pages, 9 Figures, 4 Tables. A part of this work were published in
the 2015 IEEE Information Theory Workshop, and a part was accepted for
publication in the 50th Annual Conference on Information Sciences and System
Strong Coordination over Noisy Channels: Is Separation Sufficient?
We study the problem of strong coordination of actions of two agents and
that communicate over a noisy communication channel such that the actions
follow a given joint probability distribution. We propose two novel schemes for
this noisy strong coordination problem, and derive inner bounds for the
underlying strong coordination capacity region. The first scheme is a joint
coordination-channel coding scheme that utilizes the randomness provided by the
communication channel to reduce the local randomness required in generating the
action sequence at agent . The second scheme exploits separate coordination
and channel coding where local randomness is extracted from the channel after
decoding. Finally, we present an example in which the joint scheme is able to
outperform the separate scheme in terms of coordination rate.Comment: 9 pages, 4 figures. An extended version of a paper accepted for the
IEEE International Symposium on Information Theory (ISIT), 201
Strong Coordination over Noisy Channels: Is Separation Sufficient?
We study the problem of strong coordination of actions of two agents and
that communicate over a noisy communication channel such that the actions
follow a given joint probability distribution. We propose two novel schemes for
this noisy strong coordination problem, and derive inner bounds for the
underlying strong coordination capacity region. The first scheme is a joint
coordination-channel coding scheme that utilizes the randomness provided by the
communication channel to reduce the local randomness required in generating the
action sequence at agent . The second scheme exploits separate coordination
and channel coding where local randomness is extracted from the channel after
decoding. Finally, we present an example in which the joint scheme is able to
outperform the separate scheme in terms of coordination rate.Comment: 9 pages, 4 figures. An extended version of a paper accepted for the
IEEE International Symposium on Information Theory (ISIT), 201
An Equivalence Between Secure Network and Index Coding
We extend the equivalence between network coding and index coding by Effros,
El Rouayheb, and Langberg to the secure communication setting in the presence
of an eavesdropper. Specifically, we show that the most general versions of
secure network-coding setup by Chan and Grant and the secure index-coding setup
by Dau, Skachek, and Chee, which also include the randomised encoding setting,
are equivalent
Snell's law for surface electrons: Refraction of an electron gas imaged in real space
On NaCl(100)/Cu(111) an interface state band is observed that descends from
the surface-state band of the clean copper surface. This band exhibits a
Moire-pattern-induced one-dimensional band gap, which is accompanied by strong
standing-wave patterns, as revealed in low-temperature scanning tunneling
microscopy images. At NaCl island step edges, one can directly see the
refraction of these standing waves, which obey Snell's refraction law.Comment: 4 pages, 4 figure
Conventional and manipulated growth of Cu-Cu(111)
Molecular beam epitaxy of Cu on Cu(111) was studied using thermal energy He scattering, in the temperature range between 100 and 450 K. Three-dimensional growth was observed in the whole temperature range. To determine the onset of various diffusion processes, submonolayer films formed by deposition at low temperature were annealed. Annealing proceeds in two steps. The first step is interpreted as a change in island shape, the second as Ostwald-ripening. A comparison with homoepitaxy on Pt(111) and Ag(111) is made. Growth manipulation was carried out by artificially increasing the island number density via intervention in the nucleation stage of each layer. The procedures applied were temperature reduction during nucleation as well as pulsed ion bombardment. These techniques enabled the convenient growth of good quality films consisting of a large number of monolayers. Finally, the use of oxygen as a surfactant modifying the growth mode was investigated. Under some growth conditions, pre-exposure of the surface to oxygen was found to induce weak He-intensity oscillations during deposition. The quality of the films grown in this way was, however, low
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