Search

This article details Charles Babbage’s theoretical computer program, the first attempt to specific how to mechanize complex algorithms with a computer, written in 1837. The article also discusses his theoretical computer, the Analytical Engine, that his program would have run on. Topics include Babbage’s first and second code tables and the design of the Analytical Engine.

The Association for Computing Machinery (ACM) Press is pleased to announce that the Collected Algorithms from ACM (CALGO) is now available on acm.org. as of February 1997. Originally established in 1960 as the Algorithms Department in CACM, and then transfered to Transactions on Mathematical Software in 1975, CALGO is a collection of heavily used algorithms, either in original form or translated into other languages. Planned enhancements include a cumulative SHAR classification index and the full CALGO library in CD-ROM. Contact address for any information regarding CALGO has been provided.

GLYPNER is one of the earliest existing languages designed for programming the Illiac IV computer. The syntax of the language is based on ALGOL 60, but has been extended to allow the programmer explicitly to specify the parallelism of his algorithm in terms of 64-word vectors. This paper describes the characteristics, goals, and philosophy of the language, and discusses some of the problems associated with parallel computer architectures. [ABSTRACT FROM AUTHOR]

The article discusses the algorithm in the form of abstract structure with a common database. The basic idea that could lead to this algorithm includes the reply massage sent by a node, the reception of a request massage, the interval node, and the non-consulting node. Each node implements an identical algorithm and uses two processes to enforce it. One of the processes uses the critical resource and it is known as the Request-Resource or the Release-Resource procedures. The other one deals with the received massages and it is known as the procedure Treat-Request-Massage or Treat-Release-Massage.

Logic has been around for a very long time [23]. It was already an old subject 23 centuries ago, in Aristotle's day (384-322 BC). While Aristotle was not its originator, [...]

An approach to carrying out asynchronous, distributed simulation on multiprocessor message-passing architectures is presented. This scheme differs from other distributed simulation schemes because (1) the amount of memory required by all processors together is bounded and is no more than the amount required in sequential simulation and (2) the multiprocessor network is allowed to deadlock, the deadlock is detected, and then the deadlock is broken. Proofs for the correctness of this approach are outlined. [ABSTRACT FROM AUTHOR]

We present a parallel algorithm which uses n² processors to find the connected components of an undirected graph with n vertices in time O(log²n). An O(log²n) time bound also can be achieved using only n⌈n/[log2n⌉⌉ processors. The algorithm can be used to find the transitive closure of a symmetric Boolean matrix. We assume that the processors have access to a common memory. Simultaneous access to the same location is permitted for fetch instructions but not for store instructions. [ABSTRACT FROM AUTHOR]

The concept of one event happening before another in a distributed system is examined, and is shown to define a partial ordering of the events. A distributed algorithm is given for synchronizing a system of logical clocks which can be used to totally order the events. The use of the total ordering is illustrated with a method for solving synchronization problems. The algorithm is then specialized for synchronizing physical clocks, and a bound is derived on how far out of synchrony the clocks can become. [ABSTRACT FROM AUTHOR]

Presents a technique which allows a class of solid objects to be synthesized and stored using a computer. Computational geometry; Computer-aided design; Graphics; Machined components; Polyhedra; Shape synthesis; Three-dimensional modeling.

The article presents information about candidates for members at large for the Association for Computing Machinery (ACM). Scholar Roscoe C. Giles's formal education is in theoretical physics. He received a Ph.D. from Stanford in 1975 and graduation honors in 1970. His dissertation focused on extended string-like models of strongly interacting particles and was titled "Quarks and Bubble: A Field Theory Model of Hadron Structure." His research focuses on the application of high performance and parallel computing to physics and materials problems. He has developed parallel algorithms for large scale micromagnetic modeling and molecular dynamics simulations. As an outgrowth of these computational science research efforts, he has become committed to prototyping and building computational and educational infrastructure that will enable broad participation of scholars, students and communities in computing. James Jay Horning from Inter Trust Technologies Corp., California, believes that 35 years of academic and industrial computing research have prepared him to help guide ACM programs that serve the research community, without neglecting needs of ACM's other members. ACM is currently doing many things right; several initiatives are making things better. ACM's publications have always been one of its greatest strengths.

The U.S. Government agency NIST has recently proposed a public key digital signature standard [3, 4]. Although the proposal is nominally only 'for government use,' such a proposal, if adopted, [...]

The article presents abstracts from other publications of the Association for Computing Machinery. They include "On the Structure of Armstrong Relations for Functional Dependencies," "Some Hamilton Paths and a Minimal Change Algorithm," "Random Trees and the Analysis of Branch and Bound Procedures," "Deciding Combinations of Theories" and "On Compiling Queries in Recursive First-Order Databases."

Automatic Determination of Grain Size for Efficient Parallel Processing Efficiently exploiting parallelism in programs is one of today's most critical problems in the use of parallel systems. The difficulty lies [...]

INTELLIGENCE IN SCIENTIFIC COMPUTING Combining numerical techniques with ideas from symbolic computation and with methods incorporating knowledge of science and mathematics leads to a new category of intelligent computational tools [...]