Browsing by Author "Li, Xining"
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- ItemOpen AccessCommunicating Sequential Prolog(1988-01-01) Li, Xining; Unger, Brian W; Cleary, John; Lomow, Greg; West, DarrinCommunicating Sequential Prolog (CSP') is a single-solution distributed logic programming language for discrete event simulation. Its primary goal is to speed up the execution of logic programs through the use of parallelism, while as far as possible preserving the semantics of standard Prolog. A CSP' program consists of a set of parallel processes, synchronized by simulation time and by message passing. The underlying interprocess communication mechanism is Time Warp. The pertinent features of parallel logic programming and Time Warp are described. The syntax of CSP' is introduced and the semantics of new predicates and their control structures are discussed. Examples are given to show the expressive power and simplicity of CSP'.
- ItemOpen AccessCSP*--a distributed logic programming language for discrete event simulation(1989) Li, Xining; Unger, Brian W.
- ItemOpen AccessA distributed and parallel backtracking algorithm using virtual time(1987-10-01) Cleary, John; Unger, Brian W; Li, XiningA significant problem in Logic Programming is how to execute Prolog on multiprocessor and distributed systems. For and-parallel Prolog correctly co-ordinating backtracking across many processors is difficult. An algorithm which fully supports such backtracking is described. The algorithm is based on the Virtual Time technique first described by Jefferson and Sowizral in their Time Warp system for concurrent discrete event simulation. The algorithm preserves the standard semantics of Prolog and does not require additional program control other than directives as to where goals should be run. Because of the logical semantics of Prolog optimizations of the basic Time Warp algorithm are possible. These reduce the number of rollbacks necessary and the amount of recomputation necessary after a rollback.
- ItemOpen AccessLanguages for distributed simulation(1986-10-01) Li, Xining; Unger, Brian WComputer simulation is a technique for predicting the behavior of real or hypothetical systems as these systems operate in real or hypothetical environments. Most systems and corresponding models of interest involve large numbers of concurrently operating elements, or components. This fact and the emergence of highly parallel, distributed computer systems, has led many scientists to attempt distributed simulations. There have been a number of proposals dealing with the subject of distributed simulation. In this paper, we explore some of these proposals. Three inter-process process communication mechanisms are discussed: Logical Clocks, the Network paradigm, and the Time Warp mechanism. Then, two classes of distributed programming languages are surveyed: procedural languages and declarative languages. Finally, we conclude that a Prolog-like language in conjunction with the Time Warp mechanism offers potential advantages over other approaches.
- ItemOpen AccessPredicting X-tree network performance using the JADE environment(1988-01-01) Li, Xining; Unger, Brian WJade provides an integrated set of tools which are designed to support the development of distributed software and systems. The jade environment provides tools for the design, implementation, debugging, testing, maintenance, simulation, and performance analysis of distributed, concurrent programs. A network topology called X-tree has been implemented and simulated using this Jade environment. This paper presents an overview of the Jade environment, the X-tree network topology and a robust routing algorithm for this topology. The performance of the X-tree topology is also discussed.