The European conflicts guide

This article describes a project which involved an attempt to integrate an expert system with a hypertext database of primary and secondary text materials. Our chosen legal domain was that of the Convention on Jurisdiction and the Enforcement of Judgments in Civil and Commercial Matters (The Brussels Convention 1968). In this article, we address three dimensions of system design. With regard to the legal dimension, we consider the choice of domain and the representation of both knowledge and data in the system. On the technological dimension, we discuss the selection of software development tools and problems associated with keeping knowledge bases and databases up-to-date. Finally, we pay particular attention to the Cinderella dimension of legal expert system development — the user interface.     

The new European software guide for legal metrology: Basic principles

The European guideline WELMEC 7.2 “Software Guide (Measuring Instruments Directive 2004/22/EC)” has recently been adopted. It contains requirements and validation recommendations for software in measuring instruments subject to regulations in the Measuring Instruments Directive (MID).The definition of software requirements is derived from essential MID requirements and is based on type-independent configurations of instruments and on risk classes. The definition is completed by instrument-specific requirements.Configurations of measuring instruments are divided into basic configurations of measuring instruments and extended IT configurations. Furthermore, the requirements are differentiated according to risk classes introduced in the guide.The methodology developed is applicable not only to the originally intended category of instruments, namely measuring instruments regulated by the MID, but also to far more classes of measuring instruments.     

The graph model for conflicts

The graph model for conflicts is developed as a comprehensive methodology for realistically analyzing real world conflicts. The graph form takes outcomes, rather than individual decisions, as the basic units for describing a conflict. In the graph form, many solution concepts can be formulated for both two-player and multiplayer games. In particular, specific mathematical criteria are presented for categorizing solution concepts which can be used for predicting equilibria in n-player games. One of the criteria on which this taxonomy of solution concepts is based is the number of steps ahead a player may think, in terms of the reactions of other players to his actions. Other criteria include which players take part in the sanctioning process, and whether sanctioning moves are restricted to those which lead to immediate improvements for the mover. In order to demonstrate the insight which decision makers can gain from studying a dispute using the graph model, various solution concepts are applied to an important environmental engineering problem.     

Electronic portfolios revisited: The efolios project

Electronic portfolios show considerable pedagogical, student-outcomes, and program assessment promise but have been plagued by numerous logistical and implementation problems caused by the software and by students having to learn a great deal about electronic writing to put together a viable electronic portfolio. This article describes using an efolios project to solve these problems, enabling students to concentrate on writing rather than on technology and to create an electronic environment conducive to student-outcomes and program assessment.     

Loops skewing: The wavefront method revisited

Loop skewing is a new procedure to derive the wavefront method of execution of nested loops. The wavefront method is used to execute nested loops on parallel and vector computers when none of the loops can be done in vector mode. Loop skewing is a simple transformation of loop bounds and is combined with loop interchanging to generate the wavefront. This derivation is particularly suitable for implementation in compilers that already perform automatic detection of parallelism and generation of vector and parallel code, such as are available today. Loop normalization, a loop transformation used by several vectorizing translators, is related to loop skewing, and we show how loop normalization, applied blindly, can adversely affect the parallelism detected by these translators.     

The backchase revisited

Semantic query optimization is the process of finding equivalent rewritings of an input query given constraints that hold in a database instance. In this paper, we report about a Chase & Backchase (C&B) algorithm strategy that generalizes and improves on well-known methods in the field. The implementation of our approach, the Pegasussystem, outperforms existing C&B systems an average by two orders of magnitude. This gain in performance is due to a combination of novel methods that lower the complexity in practical situations significantly.     

The sliding-window protocol revisited

We give a correctness proof of the sliding-window protocol. Both safety and liveness properties are addressed. We show how faulty channels can be represented as nondeterministic programs. The correctness proof is given as a sequence of correctness-preserving transformations of a sequential program that satisfies the original specification, with the exception that it does not have any faulty channels. We work as long as possible with a sequential program, although the transformation steps are guided by the aim of going to a distributed program. The final transformation steps consist in distributing the actions of the sequential program over a number of processes.     

The ESO method revisited

This paper examines the evolutionary structural optimisation (ESO) method and its shortcomings. By proposing a problem statement for ESO followed by an accurate sensitivity analysis a framework is presented in which ESO is mathematically justifiable. It is shown that when using a sufficiently accurate sensitivity analysis, ESO method is not prone to the problem proposed by Zhou and Rozvany (Struct Multidiscip Optim 21(1):80–83, 2001). A complementary discussion on previous communications about ESO and strategies to overcome the Zhou-Rozvany problem is also presented. Finally it is shown that even the proposed rigorous ESO approach can result in highly inefficient local optima. It is discussed that the reason behind this shortcoming is ESO’s inherent unidirectional approach. It is thus concluded that the ESO method should only be used on a very limited class of optimisation problems where the problem’s constraints demand a unidirectional approach to final solutions. It is also discussed that the Bidirectional ESO (BESO) method is not prone to this shortcoming and it is suggested that the two methods be considered as completely separate optimisation techniques.     

The stuttering principle revisited

It is known that LTL formulae without the ‘next’ operator are invariant under the so-called stutter equivalence of words. In this paper we extend this principle to general LTL formulae with given nesting depths of both ‘next’ and ‘until’ operators. This allows us to prove the semantical strictness of three natural hierarchies of LTL formulae, which are parametrized either by the nesting depth of just one of the two operators, or by both of them. Further, we provide an effective characterization of languages definable by LTL formulae with a bounded nesting depth of the ‘next’ operator.This paper is a revised and extended version of [6].     

The semantic Web revisited

The article included many scenarios in which intelligent agents and bots undertook tasks on behalf of their human or corporate owners. Of course, shopbots and auction bots abound on the Web, but these are essentially handcrafted for particular tasks: they have little ability to interact with heterogeneous data and information types. Because we haven't yet delivered large-scale, agent-based mediation, some commentators argue that the semantic Web has failed to deliver. We argue that agents can only flourish when standards are well established and that the Web standards for expressing shared meaning have progressed steadily over the past five years.     

The photon pipeline revisited

With the development of real-time ray tracing in recent years, it is now very interesting to ask if real-time performance can be achieved for high-quality rendering algorithms based on ray tracing. In this paper, we propose a pipelined architecture to implement reverse photon mapping. Our architecture can use real-time ray tracing to generate photon points and camera points, so the main challenge is how to implement the gathering phase that computes the final image. Traditionally, the gathering phase of photon mapping has only allowed coarse-grain parallelism, and this situation has been a source of inefficiency, cache thrashing, and limited throughput. To avail fine-grain pipelining and data parallelism, we arrange computations so that photons can be processed independently, similar to the way that triangles are efficiently processed in traditional real-time graphics hardware. We employ several techniques to improve cache behavior and to reduce communication overhead. Simulations show that the bandwidth requirements of this architecture are within the capacity of current and future hardware, and this suggests that photon mapping may be a good choice for real-time performance in the future.     

The occur-check problem revisited

A method is presented for executing PROLOG programs which avoids almost all unnecessary occur-checks. The method is based on a dynamic classification of the context in which logical variables occur. No static global analysis of the PROLOG program is required to detect the places where an occur-check has to be made. The presented method has also an important side benefit. It considerably cuts down on the number of memory references during the execution of PROLOG programs. Furthermore, in most cases it avoids “trailing” and “untrailing” of unbound variables altogether. Due to this fact the employed method actually speeds up PROLOG execution. The method is discussed in terms of an actual implementation based on the Warren abstract PROLOG instruction set. However, the method should be applicable to other implementation models as well. No assumptions are made with respect to particular hardware.     

The oxide cathode revisited

Abstract— A new theory is presented on the emission degradation or slump of oxide cathodes at current drawing and on the beneficial effect of doping the emitting layer with rare‐earth oxides. It was shown that during its lifetime, a gradual voltage difference is built up in the oxide layer, which eventually leads to the decomposition of BaO and O₂ during current drawing. This causes an emission slump in life‐tested cathodes. Doping with rare‐earth oxides prevents this build up due to the electron donating capability of these materials.     

Periodic timers revisited: The real-time embedded system perspective

Common sense dictates that single-shot timer mechanisms are more suitable for real-time applications than periodic ones, specially in what concerns precision and jitter. Nevertheless, real-time embedded systems are inherently periodic, with tasks whose periods are almost always known at design-time. Therefore a carefully designed periodic timer should be able to incorporate much of the advantages of single-shot timers and yet avoid hardware timers reprogramming, an expensive operation for the limited-resource platforms of typical embedded systems.In this paper, we describe and evaluate two timing mechanisms for embedded systems, one periodic and another single-shot, aiming at comparing them and identifying their strengths and weaknesses. Our experiments have shown that a properly designed periodic timer can usually match, and in some cases even outperform, the single-shot counterpart in terms of precision and interference, thus reestablishing periodic timers as a dependable alternative for real-time embedded systems.