The abstract machine and implementation of parallel Parlog

This paper defines an abstract machine for implementing the logic language Parlog on shared memory multiprocessors. A process oriented execution model is introduced that specifies the mechanisms needed to support Parlog’s control facilities and then the abstract machine is presented, which specifies data structures, the instruction set and basic operations of the machine. An implementation of this abstract machine is then described and finally a brief summary of some performance results are given of benchmark programs executed on a shared memory multiprocessor.     

Parallel branch-and-bound search in Parlog

The concurrent logic languages, of which Parlog is one, have been promoted as a new generation of software languages specifically designed for parallel programming. This paper investigates their application to a search problem commonly used as an illustration of artificial intelligence techniques, the 8-puzzle. It notes that programs written in the concurrent logic languages which do not pay attention to the parallelism can fall into two possible traps: either there is little real parallelism in them due to data dependencies, or there is too much parallelism and any practical architecture will be overwhelmed. A solution which controls the parallelism using user-defined priorities is proposed. This solution has the advantage of being architecture-independent.     

Meta-interpreters and partial evaluation in Parlog

Since logic programs are executable specifications, the main concern of logic programming, producing efficient programs, is tangential to the mainstream of formal methods. A fashionable automatic transformation technique for producing efficient programs, partial evaluation, applied to the concurrent logic programming language Parlog is discussed.     

Detection of parallel executable steps for programs with arrays

The detection of informational and logical program step dependencies is a key problem when performing equivalent transformations. In this article we consider this problem for systems of loops which represent concentration of mass computations and are the biggest challenge in parallel execution. The prototype of program formalization is C language just because of it’s popularity and it being an intermediate language for compilation of most programming languages including object-oriented ones.     

Feeding sequence selection in a manufacturing cell with four parallel machines

This paper deals with the problem of finding the optimum feeding sequence in manufacturing cells with machines fed by robots. The particular real case of a cell with four parallel identical machines working alternately on two pallets each one, fed by one robot and with random assistance requirements, is introduced and analyzed. The cell has been modelled and simulation results for different feeding sequences are presented. A general discriminant function to select the best feeding sequence between a fixed and a variable sequence was determined using simulation results for different working and loading times and pattern recognition techniques.     

SNAP: parallel processing applied to AI

It is argued that a viable solution for building future intelligent systems is to design special-purpose parallel computer architectures. The applications are restricted to those using semantic networks for knowledge representation. Reasoning on these networks is achieved with a marker-passing model of processing. The Semantic Network Array Processor (SNAP), a marker-passing parallel computer dedicated for natural-language and other knowledge-processing applications, is considered. Solutions for several nontrivial natural-language problems using the marker-passing approach are discussed     

Three steps to ethnography: A discussion of interdisciplinary contributions

In this paper recent research involving interdisciplinary ethnography is presented as an exploration of its contribution to studies of people and technology in the workplace. Three main patterns of interaction between ethnography and the others are examined. First, the influence of ethnography in promoting people-oriented perspectives of technology is discussed with reference to workplace studies in manufacturing. Second, ethnography contribution to the development of hybrid methods for the design and implementation of technology for use in the workplace is illustrated by several examples of such frameworks. Third, the influence of ethnographic research to providing a theoretical basis for computer-mediated communication is explored and documented by analyses of design teams working together as part of construction projects. From a practical point of view, this exploration has resulted in a brief discussion of the broad range of users in the real-life workplace who benefit from ethnographic research. Future work in this area will rely on a reflexive stance on the part of the ethnographer in relation to both users of technology and users of ethnography.     

10 small steps to better requirements

Project teams can take several small, easy steps to improve requirements to the point where they're good enough. But every project is different. Your team might need to take steps that wouldn't be right in other situations. The author lists 10 basic steps to improve requirements.     

Grid security: Next steps

One of the more mature instances of a service-oriented architecture is the model known as Grid computing. Computational Grids and Data Grids are becoming commonplace in certain sectors, yet the style of security they implement is suitable only for a fairly small subset of possible user communities. Using some case studies and experience, we describe the existing Grid security models, explain why they represent shortcomings for some applications, and describe some emerging architectures, Trusted Computing and virtualisation, which help address the problems.     

Taking steps to secure Web services

Despite the promise, Web services present network administrators with a thorny problem: as network security becomes an increasing concern, Web services open up networks by letting outside users access databases, applications, and internal users. Traditional security techniques - such as virtual private networks or secure sockets layer (SSL) technology - cannot secure the large number of transactions that Web services can perform in a short time. Meanwhile, basic Web services transactions are unencrypted and unsecured, which creates the potential for disaster. It is thus important for Web services technology to have its own security mechanisms. In fact, industry observers have said the biggest obstacle to wider adoption of Web services has been security concerns. With this in mind, researchers are developing and implementing several Web services security approaches.     

TETROBOT: a modular approach to parallel robotics

The TETROBOT is an actuated robotic structure which may be reassembled into many different configurations while still being controlled by the same hardware and software architecture. The TETROBOT system addresses the needs of application domains, such as space, undersea, mining, and construction, where adaptation to unstructured and changing environments and custom design for rapid implementation are required     

CODE: a unified approach to parallel programming

The authors describe CODE (computation-oriented display environment), which can be used to develop modular parallel programs graphically in an environment built around fill-in templates. It also lets programs written in any sequential language be incorporated into parallel programs targeted for any parallel architecture. Broad expressive power was obtained in CODE by including abstractions of all the dependency types that occur in the widely used parallel-computation models and by keeping the form used to specify firing rules general. The CODE programming language is a version of generalized dependency graphs designed to encode the unified parallel-computation model. A simple example is used to illustrate the abstraction level in specifying dependencies and how they are separated from the computation-unit specification. The most important CODE concepts are described by developing a declarative, hierarchical program with complex firing rules and multiple dependency types     

Designing for interaction: Six steps to designing computer-supported group-based learning

At present, the design of computer-supported group-based learning (CSGBL) is often based on subjective decisions regarding tasks, pedagogy and technology, or concepts such as ‘cooperative learning’ and ‘collaborative learning’. Critical review reveals these concepts as insufficiently substantial to serve as a basis for CSGBL design. Furthermore, the relationship between outcome and group interaction is rarely specified a priori. Thus, there is a need for a more systematic approach to designing CSGBL that focuses on the elicitation of expected interaction processes. A framework for such a process-oriented methodology is proposed. Critical elements that affect interaction are identified: learning objectives, task-type, level of pre-structuring, group size and computer support. The proposed process-oriented method aims to stimulate designers to adopt a more systematic approach to CSGBL design according to the interaction expected, while paying attention to critical elements that affect interaction. This approach may bridge the gap between observed quality of interaction and learning outcomes and foster CSGBL design that focuses on the heart of the matter: interaction.     

Five easy steps to systematic data handling

Without data, you are just another person with an opinion. However, handling or presenting your data poorly can be worse than having no data at all. Collecting and presenting solid data about a problem is one of the most effective ways to convince an audience. Yet it is surprising how often people do not take the time to present their data for maximum effect. Many mistakes can be traced to the widespread use of spreadsheets for data presentation and analysis. Not only does the default spreadsheet formatting make the data hard to read, but by automating the setup and calculation tasks, spreadsheets also can eliminate careful thought about how those tasks should be done. The author considers seven of the most common mistakes he has seen in presentations and in print. He presents five simple steps to follow every time you prepare data for presentation