Generating and approximating nondominated coteries

A coterie, which is used to realize mutual exclusion in a distributed system is a family C of incomparable subsets such that every pair of subsets in C has at least one element in common. Associate with a family of subsets C a positive (i.e., monotone) Boolean function f_c such that f_c(x)=1 if the Boolean vector x is equal to or greater than the characteristic vector of some subset in C, and 0 otherwise. It is known that C is a coterie if and only if f_c is dual-minor, and is a nondominated (ND) coterie if and only if f_c is self-dual. We introduce an operator ρ, which transforms a positive self-dual function into another positive self-dual function, and the concept of almost-self-duality, which is a close approximation to self-duality and can be checked in polynomial time (the complexity of checking positive self-duality is currently unknown). After proving several interesting properties of them, we propose a simple algorithm to check whether a given positive function is self-dual or not. Although this is not a polynomial algorithm, it is practically efficient in most cases. Finally, we present an incrementally polynomial algorithm that generates all positive self-dual functions (ND coteries) by repeatedly applying p operations. Based on this algorithm, all ND coteries of up to seven variables are computed     

Obtaining coteries that optimize the availability of replicateddatabases

Techniques for implementing the coterie scheme and for obtaining optimal coteries for a system are presented. Central to the techniques is the notion of an acceptance set, which is an alternative representation of the information contained in a coterie. Using this concept, the coterie scheme can be implemented efficiently, and an optimal coterie for a system can be obtained more directly. The problem of determining an optimal acceptance set is formulated as a sparse zero-one linear programming problem. Hence, the optimization problem can be handled using the very rich class of existing techniques for solving such problems. Experimental results indicate that the optimization approach is feasible for up to eight nodes at least. The ways in which the scheme and the optimization approach can be used for systems that distinguish between read and write operations are indicated     

Nondominated coteries on graphs

Let C and D be two distinct coteries under the vertex set V of a graph G=(V,E) that models a distributed system. Coterie C is said to G-dominate D (with respect to G) if the following condition holds: For any connected subgraph H of G that contains a quorum in D (as a subset of its vertex set), there exists a connected subgraph H' of H that contains a quorum in C. A coterie C on a graph G is said to be G-nondominated (G-ND) (with respect to G) if no coterie D(≠C) on G G-dominates C. Intuitively, a G-ND coterie consists of irreducible quorums. This paper characterizes G-ND coteries in graph theoretical terms, and presents a procedure for deciding whether or not a given coterie C is G-ND with respect to a given graph G, based on this characterization. We then improve the time complexity of the decision procedure, provided that the given coterie C is nondominated in the sense of Garcia-Molina and Barbara (1985). Finally, we characterize the class of graphs G on which the majority coterie is G-ND     

Delay optimal coteries on regular symmetric networks

Coteries, introduced by Garcia-Molina and Barbara [Journal for the Association for Computing Machinery, 32 (4) (1985) 841], are an important and effective tool for enforcing mutual exclusion in distributed systems. Communication delay is an important performance measure for a coterie. Fu et al. [IEEE Transactions on Parallel and Distributed Systems, 8 (1) (1997) 59] emphasize that while calculating communication delay, the actual distances between different sites in a network must be taken into account and using this idea, obtain delay optimal coteries for trees, rings and hypercubes. Also, topology of an interconnection network plays an important role in the performance of a distributed system. For certain applications, it is desirable that the degree of each node in the interconnection network is the same. Constant Degree Four Cayley Graphs introduced by Vadapalli and Srimani [IEEE Transactions on Parallel and Distributed Systems 7(2) (1996) 26] provide an ideal topology for such applications. They are regular, have a logarithmic diameter and a node connectivity of four. In this paper, we prove that no coterie on an arbitrary network can have a delay of less than half the diameter of the network and use this result to obtain delay optimal coteries on regular symmetric networks with special reference to constant degree four Cayley interconnection-network.     

Optimal coteries for rings and related networks

Summary Let a distributed system be represented by a graphG=(V, E), whereV is the set of nodes andE is the set of communication links. A coterie is defined as a family,C, of subsets ofV such that any pair of subsets inC has at least one node in common and no subset inC contains any other subset inC. Assuming that each nodev _i V (resp. linke _j E) is operational with probabilityp _i (resp.r _j ), the availability of a coterie is defined as the probability that the operational nodes and links ofG connect all nodes in at least one subset in the coterie. Although it is computationally intractable to find an optimal coterie that maximizes availability for general graphG, we show in this paper that, ifG is a ring, either a singleton coterie or a 3-majority coterie is optimal. Therefore, for any ring, an optimal coterie can be computed in polynomial time. This result is extended to the more general graphs, in which each biconnected component is either an edge or a ring. Toshihide Ibaraki received the B.E., M.E., and Dr. E. degrees from Kyoto University, in 1963, 1965 and 1970, respectively. Since 1969, he has been with the Department of Applied Mathematics and Physics, Kyoto University, except for two and a half years from 1983 to 1985, during which time he was with Department of Computer and Information Sciences, Toyohashi University of Technology. Currently, he is a professor of Kyoto University. He has held a number of visiting appointments with University of Illinois, University of Waterloo, Simon Fraser University, Rutgers University, and others. He is the author of Enumerative Approaches to Combinatorial Optimization, Baltzer AG., a coauthor of Resource Allocation Problems: Algorithmic Approaches, MIT Press, and the author of several books in Japanese, including Algorithms and Data Structures, Shoukohdou. His interest includes algorithms, optimization, computational complexity and their applications. Hiroshi Nagamochi was born in Tokyo, on January 1, 1960. He received the B.A., M.E. and D.E. degrees from Kyoto University, in 1983, in 1985 and in 1988, respectively. From 1988 to 1990, he was with Department of Computer and Information Sciences, Toyohashi University of Technology. Currently, he is an Associate Professor in the Department of Applied Mathematics and Physics at Kyoto University. His research interests include network flow problems and graph connectivity problems. Dr. Nagamochi is a member of the Operations Research Society of Japan and the Information Processing Society. Tsunehiko Kameda received the B.E. and M.E. degrees from the University of Tokyo in 1961 and 1963, respectively, and the Ph.D. degree from Princeton University in 1968. From 1967 to 1980, he was with the Department of Electrical Engineering, University of Waterloo. Since 1981, he has been with Simon Fraser University, Burnaby, British Columbia, Canada, where he is a Professor of Computing Science and is the Director of Computer and Communications Research Laboratory. He has held a number of visiting appointments with Universities of Erlangen-Nürnberg, Bonn, Frankfurt, and Braunschweig, and Gesellschaft für Mathematik und Datenverarbeitung, all in Germany, and also with Kyoto University, Japan. Dr. Kameda is a member of the ACM. He has co-authored three books: Einführung in die Codierungstheorie, Bibliographisches Institut, Distributed Algorithms, Kindai Kagaku-Sha, and A Probabilistic Analysis of Test Response Compaction, IEEE Press. His current research interests include database systems, combinatorial algorithms, distributed computing, ATM networks, and random testing of VLSI circuits.This work was supported in part by Grant-in-Aid from the Ministry of Education, Science and Culture of Japan, and in part by grants from the Natural Sciences and Engineering Research Council of Canada, and the Advanced Systems Institute of British Columbia.     

A geometric approach for constructing coteries and k-coteries

Quorum-based mutual exclusion algorithms are resilient to node and communication line failures. Recently, some mutual exclusion algorithms successfully use logical structures to construct coteries with small quorums sizes. In this paper, we introduce a geometric approach on dealing with the logical structures and present some useful geometric properties for constructing coteries and k-coteries. Based on those geometric properties, a logical structure named three-sided graph is proposed to provide a new scheme for constructing coteries with small quorums: The smallest quorum size is O(√N) in a homogeneous system with N nodes and O(1) in a heterogeneous system. In addition, we also extend the three-sided graph to the O-sided graph for constructing k-coteries     

Nondominated local coteries for resource allocation in grids and clouds

The resource allocation problem is a fundamental problem in Grid and Cloud computing environments. This paper focuses on constructing nondominated (ND) local coteries to solve the problem in a distributed way. Distributed algorithms using coteries usually incur low communication overheads and have high degrees of fault-tolerance, and ND coteries are candidates for the algorithms to achieve the highest degree of fault-tolerance. A new type of coteries, called p-coteries, is defined to aid the construction of local coteries. Theorems about the nondomination of p-coteries are then developed, and an operation, called pairwise-union (p-union), is proposed to help generate ND p-coteries, which in turn can be used to generate ND local coteries for solving the resource allocation problem.     

Multiobjective immune algorithm with nondominated neighbor-based selection

Abstract Nondominated Neighbor Immune Algorithm (NNIA) is proposed for multiobjective optimization by using a novel nondominated neighbor-based selection technique, an immune inspired operator, two heuristic search operators, and elitism. The unique selection technique of NNIA only selects minority isolated nondominated individuals in the population. The selected individuals are then cloned proportionally to their crowding-distance values before heuristic search. By using the nondominated neighbor-based selection and proportional cloning, NNIA pays more attention to the less-crowded regions of the current trade-off front. We compare NNIA with NSGA-II, SPEA2, PESA-II, and MISA in solving five DTLZ problems, five ZDT problems, and three low-dimensional problems. The statistical analysis based on three performance metrics including the coverage of two sets, the convergence metric, and the spacing, show that the unique selection method is effective, and NNIA is an effective algorithm for solving multiobjective optimization problems. The empirical study on NNIA's scalability with respect to the number of objectives shows that the new algorithm scales well along the number of objectives.     

Multiobjective particle swarm optimization with nondominated local and global sets

In multiobjective particle swarm optimization (MOPSO) methods, selecting the local best and the global best for each particle of the population has a great impact on the convergence and diversity of solutions, especially when optimizing problems with high number of objectives. This paper presents an approach using two sets of nondominated solutions. The ability of the proposed approach to detect the true Pareto optimal solutions and capture the shape of the Pareto front is evaluated through experiments on well-known non-trivial multiobjective test problems as well as the real-life electric power dispatch problem. The diversity of the nondominated solutions obtained is demonstrated through different measures. The proposed approach has been assessed through a comparative study with the reported results in the literature.     

Properties of an adaptive archiving algorithm for storing nondominated vectors

Search algorithms for Pareto optimization are designed to obtain multiple solutions, each offering a different trade-off of the problem objectives. To make the different solutions available at the end of an algorithm run, procedures are needed for storing them, one by one, as they are found. In a simple case, this may be achieved by placing each point that is found into an "archive" which maintains only nondominated points and discards all others. However, even a set of mutually nondominated points is potentially very large, necessitating a bound on the archive's capacity. But with such a bound in place, it is no longer obvious which points should be maintained and which discarded; we would like the archive to maintain a representative and well-distributed subset of the points generated by the search algorithm, and also that this set converges. To achieve these objectives, we propose an adaptive archiving algorithm, suitable for use with any Pareto optimization algorithm, which has various useful properties as follows. It maintains an archive of bounded size, encourages an even distribution of points across the Pareto front, is computationally efficient, and we are able to prove a form of convergence. The method proposed here maintains evenness, efficiency, and cardinality, and provably converges under certain conditions but not all. Finally, the notions underlying our convergence proofs support a new way to rigorously define what is meant by "good spread of points" across a Pareto front, in the context of grid-based archiving schemes. This leads to proofs and conjectures applicable to archive sizing and grid sizing in any Pareto optimization algorithm maintaining a grid-based archive.     

利用局部不变特征识别复杂平面多边形

提出一种基于最佳匹配点、利用交比来识别平面多边形目标的方法．该方法利用目标的顶点构造交比不变量，并以其作为目标的特征矢量．采用最大隶属度原则，首先通过局部联合矢量寻找最佳匹配点和判断目标是否丢失顶点，然后识别目标．实验表明：该方法容易实现，计算量小，识别效率高，并且能够适用目标局部缺损的情况．     

Recognizing safety and liveness

A formal characterization for safety properties and liveness properties is given in terms of the structure of the Buchi automaton that specifies the property. The characterizations permit a property to be decomposed into a safety property and a liveness property whose conjunction is the original. The characterizations also give insight into techniques required to prove a large class of safety and liveness properties.Bowen Alpern was born in 1952. He received a Ph.D. in Computer Science from Cornell University in 1986. Currently, he is a Research Staff Member in the Mathematics Department of the IBM T.J. Watson Research Center.Fred B. Schneider is an associate professor in the Computer Science Department at Cornell University. He received a Ph.D. in Computer Science from S.U.N.Y. at Stony Brook in 1978 and a B.S. from Cornell in 1975. Schneider is a member of the editorial boards of Distributed Computing and Information Processing Letters. He is also a member of the U.S. Army Committee on Recommendations for Basic Research, the College Board Committe for Advanced Placement Computer Science, IFIP Working Group 2.3 (Programming Methodology), and the Standing Organizing Committee for Principles of Distributed Computing Conferences. He has served on the program committee for PODC, POPL, SOSP, and FTCS.This work is supported, in part, by NSF Grant DCR-8320274 and Office of Naval Research contract N00014-86-K-0092     

Approximating the nondominated front using the Pareto Archived Evolution Strategy

We introduce a simple evolution scheme for multiobjective optimization problems, called the Pareto Archived Evolution Strategy (PAES). We argue that PAES may represent the simplest possible nontrivial algorithm capable of generating diverse solutions in the Pareto optimal set. The algorithm, in its simplest form, is a (1 + 1) evolution strategy employing local search but using a reference archive of previously found solutions in order to identify the approximate dominance ranking of the current and candidate solution vectors. (1 + 1)-PAES is intended to be a baseline approach against which more involved methods may be compared. It may also serve well in some real-world applications when local search seems superior to or competitive with population-based methods. We introduce (1 + lambda) and (mu + lambda) variants of PAES as extensions to the basic algorithm. Six variants of PAES are compared to variants of the Niched Pareto Genetic Algorithm and the Nondominated Sorting Genetic Algorithm over a diverse suite of six test functions. Results are analyzed and presented using techniques that reduce the attainment surfaces generated from several optimization runs into a set of univariate distributions. This allows standard statistical analysis to be carried out for comparative purposes. Our results provide strong evidence that PAES performs consistently well on a range of multiobjective optimization tasks.     

情感建模与情感识别

情感计算是关于、产生于和影响于情感方面的计算,其目的是赋予计算机识别、理解、表达和适应人情感的能力。情感计算通过各种传感器获取由人的情感所引起的表情及生理变化信号,利用“情感模型”对这些信号进行识别,从而理解人的情感并做出适当的响应。该文主要讨论了Picard教授在情感计算中情感识别部分的研究成果,着重分析了面部表情、语音、生理信号的情感模型与情感识别,这是情感计算研究的一个关键问题之一,也是建立和谐人机环境的基础之一。     

Recognizing human actions by learning and matching shape-motion prototype trees

A shape-motion prototype-based approach is introduced for action recognition. The approach represents an action as a sequence of prototypes for efficient and flexible action matching in long video sequences. During training, an action prototype tree is learned in a joint shape and motion space via hierarchical K-means clustering and each training sequence is represented as a labeled prototype sequence; then a look-up table of prototype-to-prototype distances is generated. During testing, based on a joint probability model of the actor location and action prototype, the actor is tracked while a frame-to-prototype correspondence is established by maximizing the joint probability, which is efficiently performed by searching the learned prototype tree; then actions are recognized using dynamic prototype sequence matching. Distance measures used for sequence matching are rapidly obtained by look-up table indexing, which is an order of magnitude faster than brute-force computation of frame-to-frame distances. Our approach enables robust action matching in challenging situations (such as moving cameras, dynamic backgrounds) and allows automatic alignment of action sequences. Experimental results demonstrate that our approach achieves recognition rates of 92.86 percent on a large gesture data set (with dynamic backgrounds), 100 percent on the Weizmann action data set, 95.77 percent on the KTH action data set, 88 percent on the UCF sports data set, and 87.27 percent on the CMU action data set.     

五类水体污染物质的偏振高光谱遥感实验研究

近年来高光谱遥感技术的发展极大地提高了水质指标的遥感估测精度.同时人们在通过目标的反射辐射推断目标的状态时发现,辐射中还存在另外一种丰富的潜在信息亟待研究与利用,这就是偏振光遥感信息.本文以条件稳定、可控的室内光谱实验为基础,配置铜绿微囊藻、氯化铵、硝酸钾、磷酸氢二钾和苯甲酸五个单一物质3个浓度梯度的溶液,象征性地代表叶绿素a、氨氮、硝氮、溶磷、COD五项常用水质指标,并测量获得它们的光谱偏振信息,以图形分析为主要手段,从常规光谱信息分析和偏振特征分析等方法分析各指标在350～1000nm范围内的光谱信息.研究结果表明,在常规遥感光谱中,仅有纯藻溶液和氯化铵溶液有显著响应,并可能实现其浓度反演.在偏振特征分析时发现,纯藻和氯化铵溶液的偏振振幅与空白样有明显差异,可以提高指标识别精度,磷酸氢二钾溶液也有部分特征体现,而对于硝酸钾和苯钾酸两种溶液则没有显著效果.对偏振信息的探测在一定程度上提高了部分指标的识别精度.     

用低速器件构造的高速图象识别与处理系统

介绍小尺寸运动工件实时高速图象识别与处理系统。利用手段将运动中小尺寸工件（如牙签）的图象数字化，并存储到ＭＣＳ－５１单片机中，在数字图象处理技术的基础上对小尺寸工件进行实时检测。实现了实时并行，连续运转，具有较高的性能价格比。