One of the most difficult problems in cluster analysis is the identification of the number of groups in a given data set. In this paper we offer the randomized approach in the rate distortion framework. A randomized a...
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One of the most difficult problems in cluster analysis is the identification of the number of groups in a given data set. In this paper we offer the randomized approach in the rate distortion framework. A randomized algorithm has been suggested to allocate this position. The scenario approach is used to significantly reduce the computational complexity. With ability to determine the true number of clusters and perform clustering in real-time operational mode we outline several applications in control systems and decision-making problems that can benefit from algorithm in question essentially. We also provide simulation results to show considerable speed optimization with guaranteed level of probability.
In this work we propose a computational scheme inspired by the workings of human cognition. We embed some fundamental aspects of the human cognitive system into this scheme in order to obtain a minimization of computa...
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ISBN:
(纸本)9781467351539
In this work we propose a computational scheme inspired by the workings of human cognition. We embed some fundamental aspects of the human cognitive system into this scheme in order to obtain a minimization of computational resources and the evolution of a dynamic knowledge network over time, and apply it to computer networks. Such algorithm is capable of generating suitable strategies to explore huge graphs like the Internet that are too large and too dynamic to be ever perfectly known. The developed algorithm equips each node with a local information about possible hubs which are present in its environment. Such information can be used by a node to change its connections whenever its fitness is not satisfying some given requirements. Eventually, we compare our algorithm with a randomized approach within an ecological scenario for the ICT domain, where a network of nodes carries a certain set of objects, and each node retrieves a subset at a certain time, constrained with limited resources in terms of energy and bandwidth. We show that a cognitive-inspired approach improves the overall networks topology better than a randomized algorithm.
In this paper we develop a randomized (block) coordinate descent method for solving singly linear equality constrained optimization problems that appear for example in resource allocation over networks. We show that f...
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ISBN:
(纸本)9781467320658
In this paper we develop a randomized (block) coordinate descent method for solving singly linear equality constrained optimization problems that appear for example in resource allocation over networks. We show that for strongly convex objective functions the new algorithm has an expected linear convergence rate that depends on the second smallest eigenvalue λ_2(Q) of a matrix Q that is defined in terms of the probabilities and the number of blocks. However, the computational complexity per iteration of our method is much simpler than of a method based on full gradient information. We also focus on how to choose the probabilities to make this randomized algorithm to converge as fast as possible and we arrive at solving a sparse SDP. Finally, we present some numerical results for our method that show its efficiency on huge sparse problems.
We investigate variants of Lloyd's heuristic for clustering high-dimensional data in an attempt to explain its popularity (a half century after its introduction) among practitioners, and in order to suggest improv...
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We investigate variants of Lloyd's heuristic for clustering high-dimensional data in an attempt to explain its popularity (a half century after its introduction) among practitioners, and in order to suggest improvements in its application. We propose and justify a clusterability criterion for data sets. We present variants of Lloyd's heuristic that quickly lead to provably near-optimal clustering solutions when applied to well-clusterable instances. This is the first performance guarantee for a variant of Lloyd's heuristic. The provision of a guarantee on output quality does not come at the expense of speed: some of our algorithms are candidates for being faster in practice than currently used variants of Lloyd's method. In addition, our other algorithms are faster on well-clusterable instances than recently proposed approximation algorithms, while maintaining similar guarantees on clustering quality. Our main algorithmic contribution is a novel probabilistic seeding process for the starting configuration of a Lloyd-type iteration.
Despite its reduced complexity, lattice reduction-aided decoding exhibits a widening gap to maximum-likelihood (ML) performance as the dimension increases. To improve its performance, this paper presents randomized la...
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Despite its reduced complexity, lattice reduction-aided decoding exhibits a widening gap to maximum-likelihood (ML) performance as the dimension increases. To improve its performance, this paper presents randomized lattice decoding based on Klein's sampling technique, which is a randomized version of Babai's nearest plane algorithm [i.e., successive interference cancelation (SIC)] and samples lattice points from a Gaussian-like distribution over the lattice. To find the closest lattice point, Klein's algorithm is used to sample some lattice points and the closest among those samples is chosen. Lattice reduction increases the probability of finding the closest lattice point, and only needs to be run once during preprocessing. Further, the sampling can operate very efficiently in parallel. The technical contribution of this paper is twofold: we analyze and optimize the decoding radius of sampling decoding resulting in better error performance than Klein's original algorithm, and propose a very efficient implementation of random rounding. Of particular interest is that a fixed gain in the decoding radius compared to Babai's decoding can be achieved at polynomial complexity. The proposed decoder is useful for moderate dimensions where sphere decoding becomes computationally intensive, while lattice reduction-aided decoding starts to suffer considerable loss. Simulation results demonstrate near-ML performance is achieved by a moderate number of samples, even if the dimension is as high as 32.
The present paper introduces a new model for teaching randomized learners. Our new model, though based on the classical teaching dimension model, allows to study the influence of the learner's memory size and of t...
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The present paper introduces a new model for teaching randomized learners. Our new model, though based on the classical teaching dimension model, allows to study the influence of the learner's memory size and of the presence or absence of feedback. Moreover, in the new model the order in which examples are presented may influence the teaching process. The resulting models are related to Markov decision processes, and characterizations of optimal teachers for memoryless learners with feedback and for learners with infinite memory and feedback are shown. Furthermore, in the new model it is possible to investigate new aspects of teaching like teaching from positive data only or teaching with inconsistent teachers. Characterization theorems for teachability from positive data for both ordinary teachers and inconsistent teachers with and without feedback are provided. (C) 2010 Elsevier Inc. All rights reserved.
The problem of minimum distance localization in environments that may contain self-similarities is addressed. A mobile robot is placed at an unknown location inside a 2D self-similar polygonal environment P. The robot...
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The problem of minimum distance localization in environments that may contain self-similarities is addressed. A mobile robot is placed at an unknown location inside a 2D self-similar polygonal environment P. The robot has a map of P and can compute visibility data through sensing. However the self-similarities in the environment mean that the same visibility data may correspond to several different locations. The goal, therefore, is to determine the robot's true initial location while minimizing the distance traveled by the robot. Two randomized approximation algorithms are presented that solve minimum distance localization. The performance of the proposed algorithms is evaluated empirically.
We consider the problem of efficiently enumerating the satisfying assignments to AC~0 circuits. We give a zero-error randomized algorithm which takes an AC~0 circuit as input and constructs a set of restrictions which...
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ISBN:
(纸本)9781611972108
We consider the problem of efficiently enumerating the satisfying assignments to AC~0 circuits. We give a zero-error randomized algorithm which takes an AC~0 circuit as input and constructs a set of restrictions which partitions {0, 1}~n so that under each restriction the value of the circuit is constant. Let d denote the depth of the circuit and cn denote the number of gates. This algorithm runs in time |C|2~(n(1-μc, d)) where |C| is the size of the circuit for μ_(c, d) ≥ 1/O[lg c + d lg d]~(d-1) with probability at least 1 - 2~(-n). As a result, we get improved exponential time algorithms for AC~0 circuit satisfiability and for counting solutions. In addition, we get an improved bound on the correlation of AC~0 circuits with parity.
Integer multiplication as one of the basic arithmetic functions has been in the focus of several complexity theoretical investigations and ordered binary decision diagrams (OBDDs) are one of the most common dynamic da...
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Integer multiplication as one of the basic arithmetic functions has been in the focus of several complexity theoretical investigations and ordered binary decision diagrams (OBDDs) are one of the most common dynamic data structures for Boolean functions. Only in 2008 the question whether the deterministic OBDD complexity of the most significant bit of integer multiplication is exponential has been answered affirmatively. Since probabilistic methods have turned out to be useful in almost all areas of computer science, one may ask whether randomization can help to represent the most significant bit of integer multiplication in smaller size. Here, it is proved that the randomized OBDD complexity is also exponential. (C) 2010 Elsevier B.V. All rights reserved.
We give a randomized algorithm that finds a shortest simple cycle through a given set of k vertices or edges in an n-vertex undirected graph in time 2~kn~(O(1)).
ISBN:
(纸本)9781611972108
We give a randomized algorithm that finds a shortest simple cycle through a given set of k vertices or edges in an n-vertex undirected graph in time 2~kn~(O(1)).
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