The design issues affecting a parallel implementation of the alpha-beta search algorithm are discussed with emphasis on a tree decomposition scheme that is intended for use on well-ordered trees. In particular, the principal variation splitting method has been implemented, and experimental results are presented which show how such refinements as progressive deepening, narrow window searching, and the use of memory tables affect the performance of multiprocessor-based chess playing programs. When dealing with parallel processing systems, communication delays are perhaps the greatest source of lost time. Therefore, an implementation of our tree decomposition-based algorithm is presented, one that operates with a modest amount of message passing within a network of processors. Since our system has low search overhead, the principal basis for comparison is the communication overhead, which in turn is shown to have two components. IndexTerms--Alpha-beta search, chess programs, concurrent pr...

This paper presents the technique of operator sifting as a new way of understanding both breadth-first and depth-first approaches to BDD construction. A new algorithm is also proposed to capture the breadth-first approach's advantage of memory access locality, while keeping the depth-first approach's advantage of low memory overhead. Our preliminary experimental results show that our approach is generally faster than other implementations that rely exclusively on either breadth-first or depth-first approaches while keeping memory overhead comparable to that of depth-first approaches.

In this paper we present a simple language for expressing divide and conquer computations. The language allows for many variations in the standard divide and conquer paradigm. It is implemented using the Chare Kernel parallel programming system. The Chare Kernel supports dynamic creation of work with dynamic load balancing strategies, and machine independent execution. As a result, implementation of languages and systems such as that described in this paper is simplified significantly. A translator translates divide-and-conquer programs to Chare Kernel programs, handling details of synchronization and communication automatically. The design of the language is presented, followed by a description of its implementation, and performance results on many parallel machines, including NCUBE/two, iPSC/2, and the Sequent symmetry. User programs do not have to be changed to run on any of these machines. 1 Introduction The dramatic advances in parallel computer architectures have led to an expec...

Fixed degree network development has received significant attention. This paper proposes fixed degree directed networks. Given the node degree (fan-in/out) and the size of the network (number of nodes) we propose a generic approach of contructing the topology. Our topology has minimum diameter. In addition, we provide an expansion operator Ex(x,n) to scale the network size. Network diameter increases logarithmically in the scale factor. Furhtermore we present fast routing algorithms for these networks having logarithmic time complexity while using constant buffer size. For arbitrary degrees, the routing time complexity on this family of networks is O(n 2 ); for degree 2, it is O(n), which is optimal. This paper answers Maekawas open problem (of constructing a directed degree-p network having minimal diameter for a given number of nodes) partially. 1. Introduction Elspas started researching undirected graphs of fixed degree in 1964 [7]. Given a number of nodes and fixed degree of each n...

ing out and studying those patterns of computation as useful objects in their own right leads to further insights into the nature of computation. The list operators studied later in these notes follow this approach. ffl Functional programs are usually an order of magnitude more concise than their imperative counterparts. Besides being shorter, they can be much more readable. The functional community like to cite studies that show the number of bugs per line is more or less constant, independent of the level of the language in use. Higher-level languages encode more concept per line, and therefore have relatively fewer bugs. ffl Functional programs are often more akin to formal specifications than their conventional counterparts. A good notation goes a long way towards solving the problem[47]. ffl Lazy evaluation permits a new approach to some algorithms. It is a simple but powerful idea that can remove the need for explicit backtracking, and can allow the programmer to manipulate in...