Aspects of practical implementations of PRAM algorithms

The PRAM is a shared memory model of parallel computation which abstracts away from inessential engineering details. It provides a very simple architecture independent model and provides a good programming environment. Theoreticians of the computer science community have proved that it is possible to emulate the theoretical PRAM model using current technology. Solutions have been found for effectively interconnecting processing elements, for routing data on these networks and for distributing the data among memory modules without hotspots. This thesis reviews this emulation and the possibilities it provides for large scale general purpose parallel computation. The emulation employs a bridging model which acts as an interface between the actual hardware and the PRAM model. We review the evidence that such a scheme can achieve scalable parallel performance and portable parallel software and that PRAM algorithms can be optimally implemented on such practical models. In the course of this review we presented the following new results: 1. Concerning parallel approximation algorithms, we describe an NC algorithm for findings an approximation to a minimum weight perfect matching in a complete weighted graph. The algorithm is conceptually very simple and it is also the first NC-approximation algorithm for the task with a sub-linear performance ratio. 2. Concerning graph embedding, we describe dense edge-disjoint embeddings of the complete binary tree with n leaves in the following n-node communication networks: the hypercube, the dc Bruijn and shuffle-exchange networks and the 2-dimcnsional mesh. In the embeddings the maximum distance from a leaf to the root of the tree is asymptotically optimally short. The embeddings facilitate efficient implementation of many PRAM algorithms on networks employing these graphs as interconnection networks. 3. Concerning bulk synchronous algorithmic, we describe scalable transportable algorithms for the following three commonly required types of computation; balanced tree computations. Fast Fourier Transforms and matrix multiplications

Aspects of practical implementations of PRAM algorithms

The PRAM is a shared memory model of parallel computation which abstracts away from inessential engineering details. It provides a very simple architecture independent model and provides a good programming environment. Theoreticians of the computer science community have proved that it is possible to emulate the theoretical PRAM model using current technology. Solutions have been found for effectively interconnecting processing elements, for routing data on these networks and for distributing the data among memory modules without hotspots. This thesis reviews this emulation and the possibilities it provides for large scale general purpose parallel computation. The emulation employs a bridging model which acts as an interface between the actual hardware and the PRAM model. We review the evidence that such a scheme crn achieve scalable parallel performance and portable parallel software and that PRAM algorithms can be optimally implemented on such practical models. In the course of this review we presented the following new results: 1. Concerning parallel approximation algorithms, we describe an NC algorithm for finding an approximation to a minimum weight perfect matching in a complete weighted graph. The algorithm is conceptually very simple and it is also the first NC-approximation algorithm for the task with a sub-linear performance ratio. 2. Concerning graph embedding, we describe dense edge-disjoint embeddings of the complete binary tree with n leaves in the following n-node communication networks: the hypercube, the de Bruijn and shuffle-exchange networks and the 2-dimcnsional mesh. In the embeddings the maximum distance from a leaf to the root of the tree is asymptotically optimally short. The embeddings facilitate efficient implementation of many PRAM algorithms on networks employing these graphs as interconnection networks. 3. Concerning bulk synchronous algorithmics, we describe scalable transportable algorithms for the following three commonly required types of computation; balanced tree computations. Fast Fourier Transforms and matrix multiplications

Game theory for computer games design

Designing and developing computer games can be a complex activity that may involve professionals from a variety of disciplines. In this article, we examine the use of game theory for supporting the design of game play within the different sections of a computer game, and demonstrate its application in practice via adapted high-level decision trees for modelling the flow in game play and payoff matrices for modelling skill or challenge levels

Dense edge-disjoint embedding of complete binary trees in interconnection networks

We describe dense edge-disjoint embeddings of the complete binary tree with n leaves in the following n-node communication networks: the hypercube, the de Bruijn and shuffle-exchange networks and the two-dimensional mesh. For the mesh and the shuffle-exchange graphs each edge is regarded as two parallel (or anti-parallel) edges. The embeddings have the following properties: paths of the tree are mapped onto edge-disjoint paths of the host graph and at most two tree nodes (just one of which is a leaf) are mapped onto each host node. We prove that the maximum distance from a leaf to the root of the tree is asymptotically as short as possible in all host graphs except in the case of the shuffle-exchange, in which case we conjecture that it is as short as possible. The embeddings facilitate efficient implementation of many P-RAM algorithms on these networks

Dense edge-disjoint embedding of complete binary trees in the hypercube

We show that the complete binary tree with n > 8 leaves can be embedded in the hypercube with n nodes such that: paths of the tree are mapped onto edge-disjoint paths of the hypercube, at most two tree nodes (one of which is a leaf) are mapped onto each hypercube node, and the maximum distance from a leaf to the root of the tree is log2 n + 1 hypercube edges (which is optimally short). This embedding facilitates efficient implementation of many P-RAM algorithms on the hypercube

Tuning the Zhu-Takaoka string matching algorithm and experimental results

summary:In this paper we present experimental results for string matching algorithms which have a competitive theoretical worst case run time complexity. Of these algorithms a few are already famous for their speed in practice, such as the Boyer–Moore and its derivatives. We chose to evaluate the algorithms by counting the number of comparisons made and by timing how long they took to complete a given search. Using the experimental results we were able to introduce a new string matching algorithm and compared it with the existing algorithms by experimentation. These experimental results clearly show that the new algorithm is more efficient than the existing algorithms for our chosen data sets. Using the chosen data sets over 1,500,000 separate tests were conducted to determine the most efficient algorithm

WENNER ARRAY RESISTIVITY AND SP LOGGING FOR GROUND WATER EXPLORATION IN SAWERPURAM TERI DEPOSITS, THOOTHUKUDI DISTRICT, TAMIL NADU, INDIA

ABSTRACT The objective of this study is to identify a good site for groundwater exploration in Teri deposits. In this rock types, groundwater occurs in secondary porosity developed due to weathering, faulting, fracturing in the subsurface formation. In such situations Wenner array with resistivity and SP logging is suitable method for groundwater exploration in the Teri deposits. Initially based topography, geomophological and hydrogeologial features, an area about 2km was segregate as a promising zone for groundwater exploration in the teri deposits of Sawerpuram, Thoothukudi District, Tamil Nadu, India. The Vertical Electrical Sounding was carried out using Wenner electrode configuration with help of equipment CRM 500. The interpretations were carried using Apparent Resistivity and SP logging techniques. The resistivity ranging from 100-120 Ohm.m indicates the freshwater zone in the study area

Behavioral problems and temperamental characteristics among children in alcoholic families

Background: Children of alcoholics (COAs) are at high risk for behavioral problems and temperamental difficulties. Aim: The aim of this study was to compare the behavioral problems and temperamental characteristics in children of persons with and without alcoholism. Materials and Methods: Using a case–control design, 60 children (30 in the study group and 30 controls) were evaluated for their behavioral problems, aggression, and temperamental characteristics. Tools used were: Child Behavior Checklist, Aggression Questionnaire, and the Malhotra's Temperament Schedule. Results: The COAs were found to be more aggressive, manifesting more behavioral problems and temperamental difficulties than the controls. Conclusion: Children in families with an alcohol-dependent father are at increased risk for problem behaviors with a difficult temperament

Dense edge-disjoint embedding of complete binary trees in interconnection networks

We describe dense edge-disjoint embeddings of the complete binary tree with n leaves in the following n-node communication networks: the hypercube, the de Bruijn and shuffle-exchange networks and the two-dimensional mesh. For the mesh and the shuffle-exchange graphs each edge is regarded as two parallel (or anti-parallel) edges. The embeddings have the following properties: paths of the tree are mapped onto edge-disjoint paths of the host graph and at most two tree nodes (just one of which is a leaf) are mapped onto each host node. We prove that the maximum distance from a leaf to the root of the tree is asymptotically as short as possible in all host graphs except in the case of the shuffle-exchange, in which case we conjecture that it is as short as possible. The embeddings facilitate efficient implementation of many P-RAM algorithms on these networks