Conference Paper

PLORA: A Prolog and LISP oriented RISC Architecture

April 1993

Conference: 18th International Conference for Statistics and Computer Science and its Scientific and Social Applications
At: Egypt

Authors:

Khaled Elleithy

University of Bridgeport

ResearchGate has not been able to resolve any citations for this publication.

ResearchGate has not been able to resolve any references for this publication.

Article

PROCEDIMENTO, FUNÇÃO, OBJETO OU LÓGICA? LINGUAGENS DE PROGRAMAÇÃO VISTAS PELOS SEUS PARADIGMAS

January 1970

INTRODUÇÃO A escolha da linguagem de programação para uma aplicação específica, principalmente no caso de contextos educacionais, requer uma atenção particular ao paradigma subjacente a linguagem. O objetivo deste artigo é situar algumas linguagens de programação usadas em Educação, principalmente Logo e Prolog, entre os principais paradigmas existentes, sob a ótica de "meios" diferentes onde ... [Show full abstract] problemas são representados e resolvidos. Esta abordagem às linguagens pelos seus paradigmas leva a uma reflexão sobre metodologias de uso de linguagens de programação no contexto educacional. Várias definições podem ser encontradas na literatura, para "paradigma de programação". Papert, referindo-se a linguagens suportadas por novas arquiteturas, define paradigma de programação como um "quadro estruturador1" que é subjacente à atividade de programar e coloca que a escolha do paradigma de programação pode mudar notavelmente " a maneira como o programador pensa sobre a tarefa de programar" (Papert, 1991, p.8). De acordo com a visão proposta neste artigo, esse quadro estruturador já existe no nível de abstração que linguagens como Lisp e Prolog, por exemplo, propuseram sobre a arquitetura von Neumann. Recuperando o contexto histórico da evolução das linguagens de programação, pode-se dizer que elas representam graus variados de abstração da arquitetura subjacente, chamada von Neumann.

Conference Paper

Symbolic Computing with Beowulf-Class PC Clusters

September 2000 · Lecture Notes in Computer Science

Thomas Sterling

Beowulf-class systems are an extremely inexpensive way of aggregating substantial quantities of a given resource to facilitate the execution of different kinds of potentially large workloads. Beowulf-class systems are clusters of mass-market COTS PC computers (e.g. Intel Pentium III) and network hardware (e.g. Fast Ethernet, Myrinet) employing available Unix-like open source systems software ... [Show full abstract] (e.g. Linux) to deliver superior price-performance and scalability for a wide range of applications. Initially, Beowulfs were assembled to support compute intensive applications at low cost by integrating a large number of microprocessors primarily for science and engineering problems. But over the last few years, this class of clusters has expanded in scale, application domain, and means of use to embrace a much broader range of user problem. Beowulfs have become equally important as a means of integrating large numbers of disk drives to realize large mass storage support systems for both scientific and commercial applications including data bases and transaction processing and are becoming a major workhorse for web servers and search engines. Yet, Beowulf-class systems are able to assemble together large ensembles of yet another type of resource: memory. This possibility may enable domains of computation so far largely unaddressed by the distributed cluster community. One such problem domain is symbolic computing which allows the representation and manipulation of abstract relationships among abstract objects. Once the principal tool of artificial intelligence (AI), symbolic computing has received less work than other domains as AI had garnered less attention. In the decades of the 1970s and 1980s, symbolic computation was the focus of significant effort with the development of such languages as Prolog, Scheme, OPS-5, and Common Lisp, as well as special purpose computers such as the Symbolics 3600 series and the TI Explorer. In addition, parallel symbolic computation was explored with such multiprocessor based systems as Concert and Multilisp. However, with the failure of AI to deliver results commensurate with the hype that surrounded it and the advent of more conventional RISC based systems that out performed the slower special purpose microprogrammed controlled systems, the focus on symbolic processing diminished leaving only small pockets of research in natural language processing and robotics among a few such areas. One of the factors that greatly hampered success in this regime was the inadequacy of the memory systems. Symbolic computation is memory intensive, easily consuming an order of magnitude or more of memory compared to conventional applications. Beowulf-class systems offer an alternative path to achieving large memory systems at moderate cost. A Beowulf today can provide on the order of a thousand times the memory capacity available to symbolic computing problems of the late 1980s with total memory system prices (including PC nodes and networks) of significantly less than $10 per MByte. The Beowulf Common Lisp (BCL) project is exploring the application of Beowulf class systems to scalable symbolic computation. The motivation is driven both by the opportunity that Beowulf-class systems provide through their large aggregate memory capacities and by the potential application of symbolic computing to knowledge extraction and manipulation in the realm of large scientific applications. BCL is experimenting with a merger of distributed memory hardware and a programming model based on a global name space. The semantics of Common Lisp incorporate a number of intrinsic constructs which are inherently parallel, many of which lend themselves to distributed computing. One class of such constructs is the set of functional or value oriented operators that employ copies of argument structures. Functional semantics is well known for ease of parallelization and work cast in this form can be readily distributed across cluster nodes. Common Lisp incorporates a second set of constructs referred to as mapping functions that are intrinsically parallel permitting data parallel computation across corresponding elements of complex data structures. In addition, many Lisp operators permit out of order evaluation of arguments yielding yet more natural parallelism. Some of these instructions have corresponding operators that impose ordered evaluation (e.g. LET, LET*) providing synchronization where necessary. The CLOS object oriented system is one of the most powerful in language design and provides a natural program representation for parallel distribution, as well as synchronization, and encapsulation. Finally, while not part of the formal Common Lisp language, the “futures” construct developed initially by Hewitt and later by Halstead provides an important semantic tool for distributed coordination of symbolic functions at different levels of abstraction. There are many challenges to realizing an effective Beowulf Common Lisp. These include a distributed name space directory, movement of structures and processes across system nodes, dynamic memory management with automatic garbage collection, mapping between the Lisp semantics and the MPI to hide the explicit message passing mechanisms from the programmer, and a distributed form of CLOS for BCL. This talk will describe these challenges and the path being pursued along with preliminary results showing both the feasibility and early functionality. It is believed that the availability of a scalable distributed Common Lisp for Beowulf class systems will provide an impetus to the application of symbolic computing to scientific computing and automatic knowledge abstraction extraction.

Conference Paper

VIE-KET: Frames + Prolog.

January 1985

The Vienna Knowlegde Engineering Tool is a hybrid system exploiting both the advantages of frame-based representation (inheritance!) and rule-based systems. “Rules” means more than just pure “production rules”, in fact there is a full Prolog interpreter waiting backwards for your commands. It is completly up to the knowlegde engineer to choose the right representation for his problem: either a ... [Show full abstract] pure frame system or pure Prolog or any desired combination of those two is possible within this tool. We currently implement this system in LISP on a PC. Figure 1 depicts the overall architecture of VIE-KET.

Article

Comparison of Aquarius and SPUR (Symbolic Processing upon RISC) Projects

November 1985

Two different approaches to high performance systems for Artificial Intelligence (AI) applications have been set forth at Berkeley: one by the SPUR (Symbolic Processing Upon RISC) group, the other by the Aquarius group. In particular, the SPUR group proposed multiple, homogeneous, RISCs (Reduced Instruction Set Computers) with a functional programming (LISP) paradigm while the Aquarius group ... [Show full abstract] proposes multiple, heterogeneous, specialized processors with a logic-programming (Prolog) paradigm. The two groups agreed to meet for the purpose of studying the relative merits of their two approaches and to report on their findings. Meetings were held in October and November of 1984. The meetings consisted of descriptions of the two projects and discussions of the various alternatives available. This report delineates the results of those meetings; in particular, the dissimilar objectives of the two projects are stated and a point by point discussion of the major issues are provided. The two projects are now more similar in certain aspects in which they differed a year ago. The authors describe the two projects as the are now.

Chapter

An Architectural Characterization of Prolog Execution

January 1991

We present an instruction-level profile and a higher-level operation profile obtained from simulations on a set of mid-sized Prolog programs for a load-store architecture we have developed. Our architecture serves as a platform to effectively emulate the functionality of the Warren Abstract Machine (WAM) using an enhanced, but more traditional instruction set. We compare our instruction profile ... [Show full abstract] to similar research on Pascal and Lisp to find that Prolog has a higher frequency of use of bit and shift instructions and branch and jump instructions and makes less use of loads and stores. The higher-level profile shows tag operations to be one of the costliest operations. We present and evaluate architectural enhancements to support tag operations obtaining a twenty percent performance improvement. We then look at the potential performance improvements and limitations of a pipelined implementation of our architecture. We find that the high frequency of branches and jumps and data dependencies resulting from emulating WAM operations combine to limit the benefits of a pipelined implementation.

PLORA: A Prolog and LISP oriented RISC Architecture

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