Learning classifier systems resources

 This article lists currently available sources of information on classifier systems and classifier systems research, both on-line and in print. The need for new resources, and improvements to certain existing ones, are suggested.     

On the role of Soft Computing in microelectronics technology

 This note discusses the potential of Soft Computing (SC) in microelectronics. Though the SC applications to this field have been so far rather marginal, the present trends of microelectronics technology strongly suggest that the techniques of soft computing, (fuzzy logic, neural networks, genetic algorithms, expert systems, etc.), synergistically combined with more conventional approaches, will play an increasingly relevant role.     

On Model-Based Evolutionary Computation

 Traditional evolutionary computing techniques use an explicit fitness function – mathematical or simulated – to derive a solution to a problem from a population of individuals, over a number of generations. In this paper an approach which allows such techniques to be used on problems in which evaluations are costly, which cannot be expressed formally, or which are difficult to simulate, is examined. A neural network is trained using example individuals with the explicit fitness and the resulting model of the fitness function is then used by the evolutionary algorithm to find a solution. It is shown that the approach is effective over a small range of function types in comparison to the traditional approach when limited training data is available. An iterative step is then added whereby after a number of generations the current best individual in a population is evaluated directly on the explicit fitness function. The individual and its “real” fitness are then added to the training data and the neural network is re-trained to improve its approximation of the fitness function. It is shown that in this way the performance of the model-based architecture is greatly improved on more rugged/complex landscapes without a large increase in the amount of training data required.     

On the use of registers in achieving wait-free consensus

Summary.  The computational power of concurrent data types has been the focus of much recent research. Herlihy showed that such power may be measured by the type’s ability to implement wait-free consensus. Jayanti argued that this ability could be measured in different ways, depending, for example, on whether or not read/write registers could be used in an implementation. He demonstrated the significance of this distinction by exhibiting a nondeterministic type whose ability to implement consensus was increased with the availability of registers. We show that registers cannot increase the ability to implement wait-free consensus of any deterministic type or of any type that can, without them, implement consensus for at least two processes. These results significantly impact the study of the wait-free hierarchies of concurrent data types. In particular, the combination of these results with other recent work suggests that Jayanti’s h _m hierarchy is robust for certain classes of deterministic types.     

On periodic resource scheduling for continuous-media databases

The Enhanced Pay-Per-View (EPPV) model for providing continuous-media services associates with each continuous-media clip a display frequency that depends on the clip's popularity. The aim is to increase the number of clients that can be serviced concurrently beyond the capacity limitations of available resources, while guaranteeing a constraint on the response time. This is achieved by sharing periodic continuous-media streams among multiple clients. The EPPV model offers a number of advantages over other data-sharing schemes (e.g., batching), which make it more attractive to large-scale service providers. In this paper, we provide a comprehensive study of the resource-scheduling problems associated with supporting EPPV for continuous-media clips with (possibly) different display rates, frequencies, and lengths. Our main objective is to maximize the amount of disk bandwidth that is effectively scheduled under the given data layout and storage constraints. Our formulation gives rise to -hard combinatorial optimization problems that fall within the realm of hard real-time scheduling theory. Given the intractability of the problems, we propose novel heuristic solutions with polynomial-time complexity. We also present preliminary experimental results for the average case behavior of the proposed scheduling schemes and examine how they compare to each other under different workloads. A major contribution of our work is the introduction of a robust scheduling framework that, we believe, can provide solutions for a variety of realistic EPPV resource-scheduling scenarios, as well as any scheduling problem involving regular, periodic use of a shared resource. Based on this framework, we propose various interesting research directions for extending the results presented in this paper. Received June 9, 1998 / Accepted October 13, 1998     

On the Convergence of a Multigrid Method for Linear Reaction-Diffusion Problems

In this note we consider discrete linear reaction-diffusion problems. For the discretization a standard conforming finite element method is used. For the approximate solution of the resulting discrete problem a multigrid method with a damped Jacobi or symmetric Gauss-Seidel smoother is applied. We analyze the convergence of the multigrid V- and W-cycle in the framework of the approximation- and smoothing property. The multigrid method is shown to be robust in the sense that the contraction number can be bounded by a constant smaller than one which does not depend on the mesh size or on the diffusion-reaction ratio. Received June 15, 2000     

Lower bounds for the broadcast problem in mobile radio networks

Summary.  In this paper, we prove a lower bound on the number of rounds required by a deterministic distributed protocol for broadcasting a message in radio networks whose processors do not know the identities of their neighbors. Such an assumption captures the main characteristic of mobile and wireless environments [3], i.e., the instability of the network topology. For any distributed broadcast protocol Π, for any n and for any D≦n/2, we exhibit a network G with n nodes and diameter D such that the number of rounds needed by Π for broadcasting a message in G is Ω(D log n). The result still holds even if the processors in the network use a different program and know n and D. We also consider the version of the broadcast problem in which an arbitrary number of processors issue at the same time an identical message that has to be delivered to the other processors. In such a case we prove that, even assuming that the processors know the network topology, Ω(n) rounds are required for solving the problem on a complete network (D=1) with n processors. Received: August 1994 / Accepted: August 1996     

Protocol synthesis and re-synthesis with optimal allocation of resources based on extended Petri nets

Protocol synthesis is used to derive a protocol specification, that is, the specification of a set of application components running in a distributed system of networked computers, from a specification of services (called the service specification) to be provided by the distributed application to its users. Protocol synthesis reduces design costs and errors by specifying the message exchanges between the application components, as defined by the protocol specification. In general, maintaining such a distributed application involves applying frequent minor modifications to the service specification due to changes in the user requirements. Deriving the protocol specification after each modification using the existing synthesis methods is considered expensive and time consuming. Moreover, we cannot identify what changes we should make to the protocol specification in correspondence to the changes in the service specification. In this paper, we present a new synthesis method to re-synthesize only those parts of the protocol specification that must be modified in order to satisfy the changes in the service specification. The method consists of a set of simple rules that are applied to the protocol specification written in an extended Petri net model. An application example is given along with some experimental results. Received: July 2001 / Accepted: July 2002 RID="*" ID="*" Supported by International Communications Foundation (ICF), Japan RID="**" ID="**" Supported by Communications and Information Technology Ontario (CITO) and Natural Sciences and Engineering Research Council (NSERC), Canada RID="*" ID="*" Supported by International Communications Foundation (ICF), Japan     

A system subdivision approach for large radiosity computation

O (n) for n subsystems. Moreover, the data necessary for each subsystem computation is completely localized, which allows the database to be stored on disk. The algorithm can easily be implemented with a slight modification of the hierarchical radiosity algorithm. Experiments demonstrate the efficiency of the algorithm.     

Continuity of interaction in nomadic interfaces through migration and dynamic utilization of I/O resources

The concept of ubiquitous computing reflects an infrastructure in which users are engaged in mobile interaction sessions within environments composed of dynamically varying computational resources. In this paradigm, applications are required to continuously follow end users and provide high-quality interaction while migrating among different computing devices and dynamically utilizing the available input/output (I/O) resources of each device. In the context of such interaction scenarios, the principle of continuity, which emphasizes the uninterrupted sequence of dialogue activities, is put forward as a key design goal. This paper presents an application experiment demonstrating interface migration, distributed I/O control, and dynamic I/O reconfiguration. The adopted dialogue design approach is discussed, along with the identified interaction design requirements, from the perspective of dialogue continuity. Finally, the employed software engineering strategy is presented, elaborating on the way dialogue mobility, distribution, and dynamic I/O control have been accomplished. Published online: 11 June 2002     

A self-stabilizing algorithm for the maximum flow problem

Summary.  The maximum flow problem is a fundamental problem in graph theory and combinatorial optimization with a variety of important applications. Known distributed algorithms for this problem do not tolerate faults or adjust to dynamic changes in network topology. This paper presents a distributed self-stabilizing algorithm for the maximum flow problem. Starting from an arbitrary state, the algorithm computes the maximum flow in an acyclic network in finitely many steps. Since the algorithm is self-stabilizing, it is inherently tolerant to transient faults. It can automatically adjust to topology changes and to changes in other parameters of the problem. The paper presents results obtained by extensively experimenting with the algorithm. Two main observations based on these results are (1) the algorithm requires fewer than n ² moves for almost all test cases and (2) the algorithm consistently performs at least as well as a distributed implementation of the well-known Goldberg-Tarjan algorithm for almost all test cases. The paper ends with the conjecture that the algorithm correctly computes a maximum flow even in networks that contain cycles. Received: October 1995 / Accepted: February 1997     

Algorithms for rendering realistic terrain image sequences and their parellel implementation

We present algorithms for rendering realistic images of large terrains and their implementation on a parallel computer for rapid production of terrain-animation sequences. “Large” means datasets too large for RAM. A hybrid ray-casting and projection technique incorporates quadtree subdivision techniques and filtering using precomputed bit masks. Hilbert space-filling curves determine the imagepixel rendering order. A parallel version of the algorithm is based on a Meiko parallel computer architecture, designed to relieve dataflow bottlenecks and exploit temporal image coherence. Our parallel system, incorporating 26 processors, can generate a full color-terrain image at video resolution (without noticable aliasing artifacts) every 2 s, including I/O and communication overheads.     

On the conditional expectation on probability MV-Algebras with product

 In this paper the conditional expectation is defined and a variant of the martingale convergence theorem on probability MV-algebras with product is proved.     

Some Comments on Sequencing with Controllable Processing Times

Received March 30, 2001; revised October 22, 2001