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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.

Randomized distributed computing on rings

Higham, Lisa January 1988 (has links)
The communication complexity of fundamental problems in distributed computing on an asynchronous ring are examined from both the algorithmic and lower bound perspective. A detailed study is made of the effect on complexity of a number of assumptions about the algorithms. Randomization is shown to influence both the computability and complexity of several problems. Communication complexity is also shown to exhibit varying degrees of sensitivity to additional parameters including admissibility of error, kind of error, knowledge of ring size, termination requirements, and the existence of identifiers. A unified collection of formal models of distributed computation on asynchronous rings is developed which captures the essential characteristics of a spectrum of distributed algorithms those that are error free (deterministic, Las Vegas, and nondeterministic), and those that err with small probability (Monte Carlo and nondeterministic/probabilistic). The nondeterministic and nondeterministic/probabilistic models are introduced as natural generalizations of the Las Vegas and Monte Carlo models respectively, and prove useful in deriving lower bounds. The unification helps to clarify the essential differences between the progressively more general notions of a distributed algorithm. In addition, the models reveal the sensitivity of various problems to the parameters listed above. Complexity bounds derived using these models typically vary depending on the type of algorithm being investigated. The lower bounds are complemented by algorithms with matching complexity while frequently the lower bounds hold on even more powerful models than those required by the algorithms. Among the algorithms and lower bounds presented are two specific results which stand out because of their relative significance. 1. If g is any nonconstant cyclic function of n variables, then any nondeterministic algorithm for computing g on an anonymous ring of size n has complexity [Formula Omitted] bits of communication; and, there is a is nonconstant cyclic boolean function [Formula Omitted], such that [Formula Omitted] can be computed by a Las Vegas algorithm in [Formula Omitted] expected bits of communication on a ring of size n. 2. The expected complexity of computing AND (and a number of other natural functions) on a ring of fixed size n in the Monte Carlo model is [Formula Omitted] messages and bits where [Formula Omitted] is the allowable probability of error. / Science, Faculty of / Computer Science, Department of / Graduate

The game of pentominoes

Kuttner, Michael January 1972 (has links)
A study in game-playing programming is made using the game of pentominoes which has a very large branching factor and where there exists almost no precise, factual information to guide the conduct of the play. The difficulties encountered imply that some apparent advantages of heuristic techniques are more heavily problem-dependent than is usually conceded. A guiding device capable of learning is incorporated which significantly improves the program's play in competition with versions lacking it and shows subjective improvement with human competition. / Science, Faculty of / Computer Science, Department of / Graduate

Fast algorithms to generate restricted classes of strings under rotation

Sawada, Joseph James 29 January 2018 (has links)
A necklace is a representative of an equivalence class of k-ary strings under rotation. Efficient algorithms for generating (i.e., listing) necklaces have been known for some time. Many applications, however, require a restricted class of necklaces for which no efficient generation algorithm previously existed. This dissertation addresses this problem by developing fast algorithms to generate the following restricted classes of necklaces: (a) unlabeled necklaces, (b) fixed density necklaces, (c) necklaces where the number of each alphabet symbol is fixed, (d) chord diagrams, (e) necklaces which avoid a particular Lyndon substring, and (f) bracelets. An analysis for each algorithm (a), (b), (e), and (f) shows that the amount of computation is proportional to the number of strings produced. Experimental results give a strong indication that the algorithms for (c) and (d) also achieve this time bound. In addition, a new derivation of the known formula for counting chord diagrams is presented, along with a linear time algorithm to generate a basis for the n-th homogeneous component of the free Lie algebra. / Graduate

The engineering of data structures

Colbrook, Adrian January 1990 (has links)
Abstraction in computer programming provides a means of reducing complexity by emphasising the significant information (program behaviour) whilst suppressing the immaterial (program implementation). This aids program construction, improves reliability and maintainability, and eases the application of formal correctness proofs. The importance of data abstraction in the specification, design and implementation of large systems raises the question as to whether such methods may be applied in the context of programming languages designed before the widespread use of abstraction techniques. The program structuring facilities available in FORTRAN 77 support a form of encapsulation for simple data structures. In light of this mechanism provided by the language, state-based specification was found to be most appropriate. A specification technique incorporating object-oriented techniques is particularly suitable and allows a library of object classes to be specified and then implemented in sequential FORTRAN 77. Refinement extends the object classes so as to provide the commonly occurring generators for use in iterative constructs. Therefore, the advantages of data abstraction methods may be obtained in an early procedural language such as FORTRAN 77. Data abstraction provides data independence : a change in the representation for a particular class of objects affects only the code that implements the associated operations. This allows parallel implementations to be considered, without changes to the original specification or to any user-code. The provision of such parallel data structures is required for the migration of sequential systems onto parallel distributed memory architectures. As an illustration of this approach a general 2P2-2P (for integer P≥3) search tree utilising a pipeline of processors in a distributed memory architecture is shown to provide a means of implementing the object classes. Variations in both the number of processors allocated to the pipeline and the value of P allows the optimal search structure for a given architecture to be determined. These structures are highly efficient leading to improvements in both throughput and response time as processors are added to the array. An efficient parallel implementation of object classes is therefore achieved within the tight interface provided by abstraction.

A Methodology-Independent Requirements Traceability Prototype

Moseley, Charles Warren 12 1900 (has links)
No description available.

Parallel functional programming for message-passing multiprocessors

Ostheimer, Gerald January 1993 (has links)
We propose a framework for the evaluation of implicitly parallel functional programs on message passing multiprocessors with special emphasis on the issue of load bounding. The model is based on a new encoding of the lambda-calculus in Milner's pi-calculus and combines lazy evaluation and eager (parallel) evaluation in the same framework. The pi-calculus encoding serves as the specification of a more concrete compilation scheme mapping a simple functional language into a message passing, parallel program. We show how and under which conditions we can guarantee successful load bounding based on this compilation scheme. Finally we discuss the architectural requirements for a machine to support our model efficiently and we present a simple RISC-style processor architecture which meets those criteria.

Empirical studies of novices learning programming

Jones, Ann Carolyn January 1989 (has links)
This thesis is concerned with the problems that novices have in learning to program: in particular it is concerned with the difficulties experienced by novices learning at a distance, using instructional materials which have been designed especially for novices. One of the major problems for novices is how to link the new information which they encounter with their existing knowledge. Du Boulay, O'Shea and Monk (1981) suggest helping novices to bridge the gap between their existing knowledge and new information by teaching via a conceptual model, which serves to explain the new information in familiar terms. In this thesis the difficulties which novices have when learning to program with the help of a conceptual model were investigated. The curricula and conceptual models of four different programming languages are examined, all of which were designed to teach novices. Du Boulay, O'Shea and Monk (1981) have suggested criteria for analysing conceptual models. It is argued that these criteria, however, do not address the presentation of the conceptual model, and so are insufficient to evaluate them. An additional form of analysis was proposed and used, in addition to the criteria offered by Du Boulay et al. This is a way of describing the conceptual model which distinguishes three views of the conceptual model: state, procedure and function, and which highlights the different aspects which are important for the novice learner by identifying the different kinds of knowledge which are necessary to understand the conceptual model. This analysis of the conceptual models showed that the environments are not as exemplary as the du Boulay et al's criteria suggest, and indicated that three of the environments, SOLO, PT501 and DESMOND, lack a functional representation, and that the fourth, Open Logo, has other different problems. An empirical study was carried out to study the transfer effects of learning two of the languages, a high level and a low level language, sequentially. There was no evidence for such transfer effects. The difficulties novices have in learning the four different languages were also investigated. These studies show that even though the novices were studying environments designed for novices learning at a distance, they did not develop good levels of competence, and the problems they had fall into two main categories: programming and pedagogical. Although the different languages had different aims and curricula, novices had some problems which were common to all or most of the languages. These included understanding flow of control, developing and using programming plans, developing accurate mental models, and in the high level languages, understanding recursion. It is argued that some of these problems are related to the conceptual models. In particular, the difficulties novices had in developing and using plan knowledge, which is one of their main problems, can be explained by the lack of an appropriate functional description in the languages. The subjects' pedagogical problems arose from the relationship between the style and structure of the curriculum, its content, and the subjects themselves. In all the four texts the teaching material is very carefully structured and it is suggested that this may encourage the learner to adopt an over-dependent attitude towards the text, and in some cases, to work at an inappropriate syntactic level. The relationship between the distance learning situation and the novice programmer is discussed, and recommendations are made for improving the curricula used for teaching novices programming.

Mathematical methods of linear programming

Groeneveld, Richard A. January 1963 (has links)
Thesis (M.A.)--Boston University / A complex modern society has presented its managers with the need to solve a variety of optimization problems. The desire to run a firm in such a way that profit is maximized, to schedule bombing runs to inflict a maximum of damage on an opponent consistent with acceptable losses, or to choose an assignment of available personnel which optimizes efficiency are typical examples. Such problems are called programming problems. The unifying idea here is that the limited resources (e.g. factors of production, planes, or personnel) which are available for use may be combined in a large (generally infinite) number of ways. The object is to choose from these possibilities the combination or combinations which will optimize a measure of the effectiveness of the enterprise. Mathematically, the programming problem is stated. [TRUNCATED]


De Vries, Ronald Clifford, 1936- January 1968 (has links)
No description available.

Adaptation of the multigroup reactor equations for the University of Arizona's Triga reactor to the IBM-650 computer

Gibney, Louis Garland, 1926- January 1961 (has links)
No description available.

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