Sensory stimuli are generally encoded by the activity of thousands of neurons in parallel. coding theories dealing with such high-dimensional representations face hard numerical problems. One of them is the computatio...
详细信息
Sensory stimuli are generally encoded by the activity of thousands of neurons in parallel. coding theories dealing with such high-dimensional representations face hard numerical problems. One of them is the computation of expected values according to the underlying probability distributions. Direct computations are generally avoided also because of the high numerical precision required. Here, a numerical trick is described that overcomes the problem of numerical precision, thereby providing a simple alternative to indirect methods based on stochastic sampling (Monte-Carlo methods).
We construct an abstract model based on a fundamental similarity property, which takes into account parametric dependencies and reflects a specific collection of requirements. We consider a method for masking a crypto...
详细信息
We construct an abstract model based on a fundamental similarity property, which takes into account parametric dependencies and reflects a specific collection of requirements. We consider a method for masking a cryptographic key using biometry, which satisfies the constructed model and guarantees an adequate practical security level.
A group code structure of a linear code is a description of the code as one-sided or two-sided ideal of a group algebra of a finite group. In these realizations, the group algebra is identified with the ambient space,...
详细信息
A group code structure of a linear code is a description of the code as one-sided or two-sided ideal of a group algebra of a finite group. In these realizations, the group algebra is identified with the ambient space, and the group elements with the coordinates of the ambient space. It is an obvious consequence of the definition that every p(r)-ary affine-invariant code of length pm, with p prime, can be realized as an ideal of the group algebra F-p(r) [(F-pm. +)], where (F-pm. +) is the underlying additive group of the field F-pm with p(m) elements. In this paper we describe all the group code structures of an affine-invariant code of length p(m) in terms of a family of maps from F-pm to the group of automorphisms of (F-pm, +). We also present a family of non-obvious group code structures in an arbitrary affine-invariant code. (C) 2010 Elsevier Inc. All rights reserved.
A spiking neural network that learns temporal sequences is described. A sparse code in which individual neurons represent sequences and subsequences enables multiple sequences to be stored without interference. The ne...
详细信息
A spiking neural network that learns temporal sequences is described. A sparse code in which individual neurons represent sequences and subsequences enables multiple sequences to be stored without interference. The network is founded on a model of sequence compression in the hippocampus that is robust to variation in sequence element duration and well suited to learn sequences through spike-timing dependent plasticity (STDP). Three additions to the sequence compression model underlie the sparse representation: synapses connecting the neurons of the network that are subject to STDP, a competitive plasticity rule so that neurons specialize to individual sequences, and neural depolarization after spiking so that neurons have a memory. The response to new sequence elements is determined by the neurons that have responded to the previous subsequence, according to the competitively learned synaptic connections. Numerical simulations show that the model can learn sets of intersecting sequences, presented with widely differing frequencies, with elements of varying duration.
In this paper we suggest a combined method for solving systems of Boolean polynomial equations based on testing a part of variables and using monomial compatibility criteria for dropping out some values of the tested ...
详细信息
In this paper we suggest a combined method for solving systems of Boolean polynomial equations based on testing a part of variables and using monomial compatibility criteria for dropping out some values of the tested variables. The complexity of the method is estimated for various parameters of the system.
We quantify the error statistics and patterning effects in a 5 x 40 Gbit/s WDM RZ-OOK SMF/DCF fibre link using hybrid Raman/EDFA amplification. By extensive use of a numerical model, we determine how the error statist...
详细信息
We quantify the error statistics and patterning effects in a 5 x 40 Gbit/s WDM RZ-OOK SMF/DCF fibre link using hybrid Raman/EDFA amplification. By extensive use of a numerical model, we determine how the error statistics change with the transmission distance. This knowledge is used as a basis for a constrained coding technique in order to improve the transmission error rate. We propose an adaptive constrained code for mitigation of the patterning effects and demonstrate that this approach can substantially reduce the bit error rate (BER) even for very large values of the channel BER (BER > 10(-1)). The proposed technique can be used in combination with forward error correction schemes (FEC) to extend the range of channel BERs that an FEC scheme is effective over. (C) 2011 Elsevier B.V. All rights reserved.
Weighted prediction and illumination compensation are key technologies for inter prediction in a video codec. They increase coding efficiency when the brightness of objects in a sequence fluctuates. Since most convent...
详细信息
Weighted prediction and illumination compensation are key technologies for inter prediction in a video codec. They increase coding efficiency when the brightness of objects in a sequence fluctuates. Since most conventional methods compensate for illumination changes at slice-level, they are not effective to code general sequences which have no illumination change. Proposed is a pixel based illumination compensation (PBIC) scheme which is applied to the selected pixels adaptively. The optimal IC parameters are calculated considering characteristics of each block whereas parameters of the conventional schemes are optimised for a slice. From the simulation results, it is concluded that the proposed PBIC improves the coding efficiency of high efficiency video coding (HEVC).
For an Ideal I in a regular local ring or a graded ideal I in the polynomial ring we study the limiting behavior of beta(1)(S/I-k) = dim(K) Tor(1)(S)(S/m S/I-k) as k goes to infinity By Kodiyalam s result it is known ...
详细信息
For an Ideal I in a regular local ring or a graded ideal I in the polynomial ring we study the limiting behavior of beta(1)(S/I-k) = dim(K) Tor(1)(S)(S/m S/I-k) as k goes to infinity By Kodiyalam s result it is known that beta(1)(S/I-k) is a polynomial for large k We call these polynomials the Kodiyalam polynomials and encode the limiting behavior in their generating polynomial It is shown that the limiting behavior depends only on the coefficients on the Kodiyalam polynomials in the highest possible degree For these we exhibit lower bounds in special cases and conjecture that the bounds are valid in general We also show that the Kodiyalam polynomials have weakly descending degrees and identify a situation where the polynomials all have the highest possible degree (C) 2010 Elsevier B V All rights reserved
We show that Han's bijection when restricted to permutations can be carried out in terms of the cyclic major code and the cyclic inversion code. In other words, it maps a permutation pi with cyclic major code (s(1...
详细信息
We show that Han's bijection when restricted to permutations can be carried out in terms of the cyclic major code and the cyclic inversion code. In other words, it maps a permutation pi with cyclic major code (s(1), s(2), ..., s(n)) to a permutation sigma with cyclic inversion code (s(1), s(2), ..., s(n)). We also show that the fixed points of Han's map can be characterized by the strong fixed points of Foata's second fundamental transformation. The notion of strong fixed points is related to partial Foata maps introduced by Bjorner and Wachs. (C) 2010 Elsevier Ltd. All rights reserved.
Algebraic geometric codes (or AG codes) provide a way to correct errors that occur during the transmission of digital information AG codes on curves have been studied extensively but much less work has been done for A...
详细信息
Algebraic geometric codes (or AG codes) provide a way to correct errors that occur during the transmission of digital information AG codes on curves have been studied extensively but much less work has been done for AG codes on higher dimensional varieties In particular we seek good bounds for the minimum distance We study AG codes on anticanonical surfaces coming from blow-ups of P-2 at points on a line and points on the union of two lines We can compute the dimension of such codes exactly due to known results For certain families of these codes we prove an exact result on the minimum distance For other families we obtain lower bounds on the minimum distance (C) 2010 Elsevier B V All rights reserved
暂无评论