948007
A Microeconomic Approach to Intelligent Resource Sharing in Multiagent Systems
Abstract : We have analyzed characteristics of sharable resources and developed techniques for intelligently sharing resources specifically, communication channels among agents in multiagent systems. Our techniques allow agents to nearly optimize their communication behavior in a self-organizing and distributed fashion, involving the use of a microeconomic pricing system based on economic laws of supply and demand and trading among agents in real-time. Our analyses are based on three measures of performance: fairness of resource allocation, waiting time for resources, and utilization of resources. Our initial analysis indicates that fairness and utilization are conflicting, in that the best utilization with a fair allocation is equivalent to the worst utilization with an unfair resource allocation, assuming the allocation policy is statically defined. To strike a balance in performance, we have developed mechanisms that establish an artificial economy, where agents can dynamically reallocate goods (resource access) using a competitive market pricing mechanism. However, unlike more common market-oriented methods, our approach does not demand convergence to equilibrium, but permits more rapid, heuristic trading, leading to near optimal performance where both buyers and sellers of resources can benefit. Our studies show that agents employing our mechanisms can dramatically improve utilization while still providing fair access to the resources.
16948552
Structured Circuit Semantics for Reactive Plan Execution Systems
A variety of reactive plan execution systems have been developed in recent years, each attempting to solve the problem of taking reasonable courses of action fast enough in a dynamically changing world. Comparing these competing approaches, and collecting the best features of each, has been problematic because of the diverse representations and (sometimes implicit) control structures that they have employed. To rectify this problem, we have extended the circuit semantics notion of teleo-reactive programs into richer, yet compact semantics, called structured circuit semantics (SCS), that can be used to explicitly represent the control behavior of various reactive execution systems. By transforming existing systems into SCS, we can identify underlying control assumptions and begin to identify more rigorously the strengths and limitations of these systems. Moreover, SCS provides a basis for constructing new reactive execution systems, with more understandable semantics, that can be tailored to particular domain needs.
7800252
Imprecise data computation for high performance asynchronous processors
Instruction level parallelism(ILP) is strictly limited by various dependencies. In particular , data dependency is the major performance bottleneck of data intensive applications. To accelerate the execution of sequential code serialized due to data dependencies, this paper proposes an imprecise computation as a fast data computing technique for a high-performance asynchronous processor. To show the performance benefits of the suggested computing model, simulation results are presented. The imprecise computation can be used effectively in data intensive processing with a microprocessor, a Digital Signal Processor or a multimedia processor.
1519617
Distributed parallel data storage systems: a scalable approach to high speed image servers
We have designed, built, and analyzed a distributed parallel storage system that will supply image streams fast enough to permit multi-user, “real-time”, video-like applications in a wide-area ATM network-based Internet environment. We have based the implementation on user-level code in order to secure portability; we have characterized the performance bottlenecks arising from operating system and hardware issues, and based on this have optimized our design to make the best use of the available performance. Although at this time we have only operated with a few classes of data, the approach appears to be capable of providing a scalable, high-performance, and economical mechanism to provide a data storage system for several classes of data (including mixed multimedia streams), and for applications (clients) that operate in a high-speed network environment.
13362734
FINDIT: a fast and intelligent subspace clustering algorithm using dimension voting
Abstract The aim of this paper is to present a novel subspace clustering method named FINDIT. Clustering is the process of finding interesting patterns residing in the dataset by grouping similar data objects from dissimilar ones based on their dimensional values. Subspace clustering is a new area of clustering which achieves the clustering goal in high dimension by allowing clusters to be formed with their own correlated dimensions. In subspace clustering, selecting correct dimensions is very important because the distance between points is easily changed according to the selected dimensions. However, to select dimensions correctly is difficult, because data grouping and dimension selecting should be performed simultaneously. FINDIT determines the correlated dimensions for each cluster based on two key ideas: dimension-oriented distance measure which fully utilizes dimensional difference information, and dimension voting policy which determines important dimensions in a probabilistic way based on V nearest neighbors' information. Through various experiments on synthetic data, FINDIT is shown to be very successful in the high dimensional clustering problem. FINDIT satisfies most requirements for good clustering methods such as accuracy of results, robustness to the noise and the cluster density, and scalability to the dataset size and the dimensionality. Moreover, it is gracefully scalable to full dimension without any modification to algorithm.
10209884
Downlink power allocation for multi-class wireless systems
In this paper we consider a power allocation problem in multi-class wireless systems. We focus on the downlink of the system. Each mobile has a utility function that characterizes its degree of satisfaction for the received service. The objective is to obtain a power allocation that maximizes the total system utility. Typically, natural utility functions for each mobile are nonconcave. Hence, we cannot use existing convex optimization techniques to derive a global optimal solution. We develop a simple (distributed) algorithm to obtain a power allocation that is asymptotically optimal in the number of mobiles. The algorithm is based on dynamic pricing and consists of two stages. At the mobile selection stage, the base station selects mobiles to which power is allocated. At the power allocation stage, the base station allocates power to the selected mobiles. We provide numerical results that illustrate the performance of our scheme. In particular, we show that our algorithm results in system performance that is close to the performance of a global optimal solution in most cases.
7043785
A new family of authentication protocols
We present a related family of authentication and digital signature protocols based on symmetric cryptographic primitives which perform substantially better than previous constructions. Previously, one-time digital signatures based on hash functions involved hundreds of hash function computations for each signature; we show that given online access to a timestamping service, we can sign messages using only two computations of a hash function. Previously, techniques to sign infinite streams involved one such one-time signature for each message block; we show that in many realistic scenarios a small number of hash function computations is sufficient. Previously, the Diffie Hellman protocol enabled two principals to create a confidentiality key from scratch: we provide an equivalent protocol for integrity, which enables two people who do not share a secret to set up a securely serialised channel into which attackers cannot subsequently intrude. In addition to being of potential use in real applications, our constructions also raise interesting questions about the definition of a digital signature, and the relationship between integrity and authenticity.