14954595
Macroscopic model of agent-based load balancing on grids
We present a dynamic model of agent-based load balancing on grids. Our goal is to explore the effects of agents' strategies on the quality of load balancing. We show that under certain conditions, the model exhibits a known phenomenon that the load is perfectly balanced. This result is in agreement with recent experimental results on load balancing through Anthill. On the other hand, under general conditions, our model predicts unexpected phenomena that all the load balancing states tend to a unique steady state, where the load is not absolutely even balanced. The quality of load balancing, e.g., whether or not the load can be perfectly balanced, depends on agents' strategies. To measure the quality of load balancing, we define a total utility gain and further discuss the optimization of total utility gains.
18067929
Multiagent SAT (MASSAT): Autonomous Pattern Search in Constrained Domains
In this paper, we present an autonomous pattern search approachto solving Satisfiability Problems (SATs). Our approach is essentially a multiagent system. To solve a SAT problem, we first divide variables into groups, and represent each variable group with an agent. Then, we randomly place each agent onto a position in the correspoding local space which is composed of the domains of the variables that are represented by this agent. Thereafter, all agents will autonomously make searchdecisions guided by some reactive rules in their local spaces until a special pattern (i.e., solution) is found or a time step threshold is reached. Experimental results on some benchmark SAT test-sets have shown that by employing the MASSAT approach, we can obtain performances comparable to those of other popular algorithms.
5692814
Mining associated implication networks: computational intermarket analysis
Current attempts to analyze international financial markets include the use of financial technical analysis and data mining techniques. In this paper, we propose a new approach that incorporates implication networks and association rules to form an associated network structure. The proposed approach explicitly addresses the issue of local vs. global influences between financial markets.
14178256
Distributed Problem Solving Without Communication - An Examination of Computationally Hard Satisfiability Problems
In this paper, we extend and modify the ERA approach proposed in Ref. 13 to solve Propositional Satisfiability Problems (SATs). The new ERA approach involves a multiagent system where each agent only senses its local environment and applies some self-organizing rules for governing its movements. The environment, which is a two-dimensional cellular environment, records and updates the local values that are computed and affected according to the movements of individual agents. In solving a SAT with the ERA approach, we first divide variables into several groups, and represent each variable group with an agent whose possible positions correspond to the elements in a Cartesian product of variable domains, and then randomly place each agent onto one of its possible positions. Thereafter, the ERA system will keep on dispatching agents to choose their movements until an exact or approximate solution emerges. The experimental results on some benchmark SAT test-sets have shown that the ERA approach can obtain comparable results as well as stable performances for SAT problems. In particular, it can find approximate solutions for SAT problems in only a few steps. The real value of this approach is that it is a distributed asynchronous approach without any centralized control or evaluation, where the agents can cooperate to solve problems without explicit communication.
37683026
Web Intelligence (WI)
The 21st century is the age of the Internet and the World Wide Web. The Web revolutionizes the way we gather, process, and use information. At the same time, it also redefines the meanings and processes of business, commerce, marketing, finance, publishing, education, research, development, as well as other aspects of our daily life. The revolution is just beginning. Although individual Web based information systems are constantly being deployed, advanced issues and techniques for developing and for benefiting from Web intelligence still remain to be systematically studied. The article defines a new research field, namely Web Intelligence (WI) by giving a complete picture of WI related topics for systematic study on advanced Web technology and developing Web based intelligent information systems. Roughly speaking, WI exploits AI and advanced information technology on the Web and Internet. It is the key and the most urgent research field of IT for business intelligence.
33842812
Anycast-Based Cooperative Proxy Caching
As one of the most popular applications currently running on the Internet, the World Wide Web is of an exponential growth in size, which results in the network congestion and server overloading. Web caching as an important technique aims at reducing network traffic, server load, and user-perceived retrieval delays by replicating popular contents on proxy caches. In our paper, we develop an anycast-based cooperative web proxy caching mechanism. It puts response time, hop counts, self-organized load balancing, adaption, and self-configuration as primary concerns. In our scheme, anycast is used to bring a server “nearest” to a client to improve overall performance, all proxies in a local network consists an anycast group. The object placement and replacement problems are formulated as an optimization problem and the solution is obtained by using an anycast-based cooperative proxy caching algorithm. Some simulation experiments have been conduced to evaluate the proposed scheme in terms of a wide range of performance metrics. Analytical and experimental results show that our algorithm outperforms some existing algorithms in response time, hop counts.
16023163
Analysis and Characterization of Intel Itanium Instruction Bundles for Improving VLIW Processor Performance
In order to achieve high instruction level parallelism (ILP), designers are turning to very long instruction word (VLIW) based designs, in which different types of instructions are grouped together as bundles of 128 bits or longer. In VLIW, the added nops increase the code size, limit processor performance by the under-utilization of functional units. In examining these performance issues of VLIW systems, we consider Intel first 64-bit architecture, the IA-64, and its first implementation, the Itanium, which employs Intel version of VLIW. We present a comprehensive analysis of the problem of under-utilization due to nops and stops across a wide range of application domains through the use of three different benchmark suites: SPEC CPU 2000, MediaBench, and PacketBench. Our results show that, on average, nops create an under-utilization factor of 28.46% in the case of SPEC CPU, 32.27% in MediaBench, and 29.76% in PacketBench. We also analyze the characteristics of different instruction bundle formats, which we obtain by collecting statistics concerning the frequency of the bundle formats
28349358
Data Parallel Program Design
We have shown how graphical languages such as CODE/ROPE and PPSE can be used to design SIMD or data parallel programs. The advantages of this approach are machine independence, design clarity, automated program analysis, and accelerated software development. The disadvantages are that many problems remain in this approach such as how to reduce design clutter, how to automate optimal processor mapping, and how to perform messagepassing optimization. More work is needed before this approach can be used in the design of large-scale applications, but we believe the approach is promising. The main contribution is to show how the simple ideas of stencils, stream generators, and replicators can be used effectively to extend the classical dataflow design paradigm into the data parallel design paradigm. While more work is needed, these three ideas lead to greater expressiveness of design. The PPSE toolset currently does much of the mapping, scheduling, and automatic code generation described in this paper. However, PPSE does not currently handle data parallel programming. Work is progressing toward a full implementation of these ideas. Even so, PPSE has been invaluable for performing a variety of what-if analyses on parallel programs. Insights have been gained with this approach that would not be possible with a purely textual representation of the parallel program.
7417284
Load Balancing in Hypercubic Distributed Hash Tables with Heterogeneous Processors
There has been a considerable amount of recent research on load balancing for distributed hash tables (DHTs), a fundamental tool in Peer-to-Peer networks. Previous work in this area makes the assumption of homogeneous processors, where each processor has the same power. Here, we study load balancing strategies for a class of DHTs, called hypercubic DHTs, with heterogenous processors. We assume that each processor has a size, representing its resource capabilities, and our objective is to balance the load density (load divided by size) over the processors in the system. Our main focus is the offline version of this load balancing problem, where all of the processor sizes are known in advance. This reduces to a natural question concerning the construction of binary trees. Our main result is an efficient algorithm for this problem. The algorithm is simple to describe, but proving that it does in fact solve our binary tree construction problem is not so simple. We also give upper and lower bounds on the competitive ratio of the online version of the problem.
5135154
Linking UML models of design and requirement
Both a UML model of requirement and a UML model of a design are defined as a pair of class diagram and a family of sequence diagrams. We then give an unified semantics for models of requirements and designs. We define the consistency between a design class diagram and the interaction diagrams and show how the removal of inconsistency can be treated as a model refinement. We then formally define the correctness of UML model of design with respect to the model of requirement.
343488
An implementation of the SSF scalable simulation framework on the Cray MTA
Large-scale parallel discrete event simulations of massive networks, such as the Internet, are "Grand Challenge" problems: packet level simulation of even a small fraction of the Internet would consume the resources of the most powerful computers available. We reimplement the SSF scalable simulation framework so we can run large-scale network simulations originally written for DaSSF. Our implementation, CraySSF, is designed for the Cray-MTA, a multithreaded supercomputer architecture developed specifically to address large-scale computations of the kind that are not easily distributed. We describe the architecture, implementation issues, and preliminary performance results on a variety of (stock) serial and parallel architectures.