High-performance computer architecture

Graphs, Groups and Surfaces.

The Computer from Pascal to von Neumann

The construction of an omnicient endgame data base

Due to the witnessed prevalence of the commercial multi-core microprocessors, parallel programming becomes a dire need for efficiently using all available hardware resources for one application. One of the parallel programming approaches is multithreading, which has been proved to play a great role in providing sequential computers with virtual parallelisation, yielding faster execution and easy communication. Such advantageous features are provided through creating a dynamic number of concurrent threads at run-time of an application. Based on these facts, this paper presents a parallel multithreaded approach for the well-known iterative deepening A* (IDA*) heuristic search algorithm using POSIX threads (Pthreads) and message-passing interface libraries running on 16 dual-core processors. The feasibility of the parallel multithreaded approach is investigated as an alternative for hosting applications requiring intensive graph search. The analytical evaluation and experimental results revealed the improved performance achieved by the proposed parallel multithreaded IDA* algorithm.

Parallel multithreaded IDA* heuristic search: algorithm design and performance evaluation

This thesis describes techniques for the design of parallel programs that solve well-structured problems with inherent symmetry. Part I demonstrates the reduction of such problems to generalized matrix multiplication by a group-equivariant matrix. Fast techniques for this multiplication are described, including factorization, orbit decomposition, and Fourier transforms over nite groups. Our algorithms entail interaction between two symmetry groups: one arising at the software level from the problem's symmetry and the other arising at the hardware level from the processors' communication network. Part II illustrates the applicability of our symmetry-exploitation techniques by presenting a series of case studies of the design and implementation of parallel programs. First, a parallel program that solves chess endgames by factorization of an associated dihedral group-equivariant matrix is described. This code runs faster than previous serial programs, and discovered a number of results. Second, parallel algorithms for Fourier transforms for nite groups are developed, and preliminary parallel implementations for group transforms of dihedral and of symmetric groups are described. Applications in learning, vision, pattern recognition, and statistics are pro-

Basel Mahafzah

Papers

A Framework for Performance Assessment of Parallel Bi-Directorial Heuristic Search.