1,071,591 research outputs found
Energy-Efficient Algorithms
We initiate the systematic study of the energy complexity of algorithms (in
addition to time and space complexity) based on Landauer's Principle in
physics, which gives a lower bound on the amount of energy a system must
dissipate if it destroys information. We propose energy-aware variations of
three standard models of computation: circuit RAM, word RAM, and
transdichotomous RAM. On top of these models, we build familiar high-level
primitives such as control logic, memory allocation, and garbage collection
with zero energy complexity and only constant-factor overheads in space and
time complexity, enabling simple expression of energy-efficient algorithms. We
analyze several classic algorithms in our models and develop low-energy
variations: comparison sort, insertion sort, counting sort, breadth-first
search, Bellman-Ford, Floyd-Warshall, matrix all-pairs shortest paths, AVL
trees, binary heaps, and dynamic arrays. We explore the time/space/energy
trade-off and develop several general techniques for analyzing algorithms and
reducing their energy complexity. These results lay a theoretical foundation
for a new field of semi-reversible computing and provide a new framework for
the investigation of algorithms.Comment: 40 pages, 8 pdf figures, full version of work published in ITCS 201
Bounds on topological Abelian string-vortex and string-cigar from information-entropic measure
In this work we obtain bounds on the topological Abelian string-vortex and on
the string-cigar, by using a new measure of configurational complexity, known
as configurational entropy. In this way, the information-theoretical measure of
six-dimensional braneworlds scenarios are capable to probe situations where the
parameters responsible for the brane thickness are arbitrary. The so-called
configurational entropy (CE) selects the best value of the parameter in the
model. This is accomplished by minimizing the CE, namely, by selecting the most
appropriate parameters in the model that correspond to the most organized
system, based upon the Shannon information theory. This information-theoretical
measure of complexity provides a complementary perspective to situations where
strictly energy-based arguments are inconclusive. We show that the higher the
energy the higher the CE, what shows an important correlation between the
energy of the a localized field configuration and its associated entropic
measure.Comment: 6 pages, 7 figures, final version to appear in Phys. Lett.
Simulating Noisy Channel Interaction
We show that rounds of interaction over the binary symmetric channel
with feedback can be simulated with
rounds of interaction over a noiseless channel. We also introduce a more
general "energy cost" model of interaction over a noisy channel. We show energy
cost to be equivalent to external information complexity, which implies that
our simulation results are unlikely to carry over to energy complexity. Our
main technical innovation is a self-reduction from simulating a noisy channel
to simulating a slightly-less-noisy channel, which may have other applications
in the area of interactive compression
On the complexity and the information content of cosmic structures
The emergence of cosmic structure is commonly considered one of the most
complex phenomena in Nature. However, this complexity has never been defined
nor measured in a quantitative and objective way. In this work we propose a
method to measure the information content of cosmic structure and to quantify
the complexity that emerges from it, based on Information Theory. The emergence
of complex evolutionary patterns is studied with a statistical symbolic
analysis of the datastream produced by state-of-the-art cosmological
simulations of forming galaxy clusters. This powerful approach allows us to
measure how many bits of information are necessary to predict the evolution of
energy fields in a statistical way, and it offers a simple way to quantify
when, where and how the cosmic gas behaves in complex ways. The most complex
behaviors are found in the peripheral regions of galaxy clusters, where
supersonic flows drive shocks and large energy fluctuations over a few tens of
million years. Describing the evolution of magnetic energy requires at least a
twice as large amount of bits than for the other energy fields. When radiative
cooling and feedback from galaxy formation are considered, the cosmic gas is
overall found to double its degree of complexity. In the future, Cosmic
Information Theory can significantly increase our understanding of the
emergence of cosmic structure as it represents an innovative framework to
design and analyze complex simulations of the Universe in a simple, yet
powerful way.Comment: 15 pages, 14 figures. MNRAS accepted, in pres
Novel Feedback Calculation Technique for Improved Transmit Scheme
Extended balanced space-time block coding (EBSTBC) is able to achieve large coding gain and guarantee full diversity for any number of transmit antennas. Performance of the EBSTBC has been improved with improved transmit scheme (ITS) which is combination of the EBSTBC with transmit antenna selection. Performance of the ITS with a limited number of feedback bits approaches to performance of ideal beamforming which requires ideal channel state information at the transmitter. However, the calculation of feedback information at the receiver employs exhaustive searching scheme which is very complex and energy inefficient process. In this work, a low complexity and energy efficient feedback information scheme for the ITS receiver is proposed. Theoretical and simulation results show that the calculation complexity of feedback information is decreased more than 87% and the proposed scheme yields the same bit error rate performance with the ITS. Moreover, the proposed scheme requires very low addition memory with respect to alternative schemes
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