Impagliazzo and Wigderson proved a uniform hardness vs. randomness "gap result" for BPP. We show an analogous result for AM: Either Arthur-Merlin protocols are very strong and everything in E=DTIME(2/sup O(n...
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Impagliazzo and Wigderson proved a uniform hardness vs. randomness "gap result" for BPP. We show an analogous result for AM: Either Arthur-Merlin protocols are very strong and everything in E=DTIME(2/sup O(n)/) can be proved to a subexponential time verifier, or else Arthur-Merlin protocols are weak and every language in AM has a polynomial time nondeterministic algorithm in the uniform average-case setting (i.e., it is infeasible to come up with inputs on which the algorithm fails). For the class AM/spl cap/coAM, we can remove the average-case clause and show under the same assumption that AM/spl cap/coAM=NP/spl cap/coNP. A new ingredient in our proof is identifying a novel resiliency property of hardness vs. randomness trade-offs. We observe that the Miltersen-Vinodchandran generator has this property.
The impulse response of an FIR lowpass or highpass filter is quasi-periodic and enclosed in an envelope with diminishing magnitude. Its energy concentrates near the center. This diminishing energy and quasi-periodic n...
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ISBN:
(纸本)0780377028
The impulse response of an FIR lowpass or highpass filter is quasi-periodic and enclosed in an envelope with diminishing magnitude. Its energy concentrates near the center. This diminishing energy and quasi-periodic nature of the impulse response have been exploited in Y.C. Lim (1990) to reduce the complexity of an FIR filter using a scheme called the extrapolated impulse response technique. In this paper, a semi-infinite programming is proposed to jointly optimize the filter coefficients and the extrapolated scaling factors. A realization structure making use of the coefficient symmetry is also presented. An example taken from literature is included illustrating that the number of multipliers for the resulting filter is less than 65 percent of existing results.
Human perception is a complex nonlinear dynamics. On the one hand it is periodic dynamics and on the other hand it is chaotic. Thus, we wish to propose a hybrid-the spatial chaotic dynamics for the associative recall ...
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Human perception is a complex nonlinear dynamics. On the one hand it is periodic dynamics and on the other hand it is chaotic. Thus, we wish to propose a hybrid-the spatial chaotic dynamics for the associative recall to retrieve patterns, similar to Walter Freeman's discovery, and the fixed point dynamics for memory stage, similar to Hopfield and Grossberg's discoveries. In this model, each neuron in the network could be a chaotic map, whose phase space is divided into two states: one is periodic dynamic state with period-V, which is used to represent a V-value retrieved pattern; another is chaotic dynamic state. Firstly, patters are stored in the memory by fixed point learning algorithm. In the retrieving process, all neurons are initially set in the chaotic region. Due to the ergodicity property of chaos, each neuron will approximate the periodic points covered by the chaotic attractor at same instants. When this occurs, the control is activated to drive the dynamic of each neuron to their corresponding stable periodic point. computer simulations confirm the theoretical prediction.
Rate and diversity impose a fundamental trade-off in space-time coding. High-rate space-time codes come at a cost of lower diversity, and high reliability (diversity) implies a lower rate. We explore a different point...
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Rate and diversity impose a fundamental trade-off in space-time coding. High-rate space-time codes come at a cost of lower diversity, and high reliability (diversity) implies a lower rate. We explore a different point of view where we design high-rate space-time codes that have a high-diversity code embedded within them. This allows a form of communication where the high-rate code opportunistically takes advantage of good channel realizations whereas the embedded high-diversity code ensures that at least part of the information is received reliably. We explore this point of view with design issues, along with some preliminary progress on code constructions and some information-theoretic considerations.
The detection characteristics of an indoor-optical communication system, which utilizes infrared radiation as carrier has been explored and enhanced for telemedicine, and wireless local area network applications. The ...
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The detection characteristics of an indoor-optical communication system, which utilizes infrared radiation as carrier has been explored and enhanced for telemedicine, and wireless local area network applications. The novelty of the presented technique consists in the fact that multipath dispersion can be reduced under controlled polarization link setup. The design of such a network is based on the specifications set by the IEEE 802.11 standard. Significant noise reduction has been achieved by utilizing wavelet transform processing algorithms.
In wireless communication, the signal of a typical broadcast station is transmitted from a broadcast center p and reaches objects at a distance, say, r from it. In addition there is a radius r 0 , r 0 < r, such tha...
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In wireless communication, the signal of a typical broadcast station is transmitted from a broadcast center p and reaches objects at a distance, say, r from it. In addition there is a radius r 0 , r 0 < r, such that the signal originating from the center of the station is so strong that human habitation within distance r 0 from the center p should be avoided. In other words, points within distance r 0 from the station comprise a hazardous zone. We consider the following station layout proble: Cover a given planar region that includes a collection of buildings with a minimum number of stations so that every point in the region is within the reach of a station, while at the same time no interior point of any building is within the hazardous zone of a station. We give algorithms for computing such station layouts in both the one- and two-dimensional cases.
We study the theory and design of efficient combinatorial and probabilistic group testing procedures. Particular attention is paid to two-stage tests because of their importance in such applications as monoclonal anti...
This note considers the problem of finding a stable reduced-order model for a given stable model so that its H/sub 2/ model reduction cost differs by less than a prescribed error from the optimal cost, which may or ma...
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This note considers the problem of finding a stable reduced-order model for a given stable model so that its H/sub 2/ model reduction cost differs by less than a prescribed error from the optimal cost, which may or may not be achievable. It is shown that this new version of the long-standing H/sub 2/ optimal model reduction problem can be reduced to a well-posed smooth constrained minimization problem whose global solution is guaranteed to exist. In addition, a globally convergent algorithm in the form of an ordinary differential equation is derived.
We use importance sampling to analyze polarization-mode dispersion (PMD) compensators that consist of a single differential-group delay (DGD) element. Using this technique we show that while these compensators improve...
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