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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.
21

Data structures and algorithms for data representation in constrained environments

Karras, Panagiotis. January 2007 (has links)
published_or_final_version / abstract / Computer Science / Doctoral / Doctor of Philosophy
22

Improved indexes for next generation bioinformatics applications

Wu, Man-kit, Edward., 胡文傑. January 2009 (has links)
published_or_final_version / Computer Science / Master / Master of Philosophy
23

Higher order strictness analysis by abstract interpretation over finite domains

Ferguson, Alexander B. January 1995 (has links)
No description available.
24

Solving Geometric Problems in Space-Conscious Models

Chen, Yu January 2009 (has links)
When dealing with massive data sets, standard algorithms may easily ``run out of memory''. In this thesis, we design efficient algorithms in space-conscious models. In particular, in-place algorithms, multi-pass algorithms, read-only algorithms, and stream-sort algorithms are studied, and the focus is on fundamental geometric problems, such as 2D convex hulls, 3D convex hulls, Voronoi diagrams and nearest neighbor queries, Klee's measure problem, and low-dimensional linear programming. In-place algorithms only use O(1) extra space besides the input array. We present a data structure for 2D nearest neighbor queries and algorithms for Klee's measure problem in this model. Algorithms in the multi-pass model only make read-only sequential access to the input, and use sublinear working space and small (usually a constant) number of passes on the input. We present algorithms and lower bounds for many problems, including low-dimensional linear programming and convex hulls, in this model. Algorithms in the read-only model only make read-only random access to the input array, and use sublinear working space. We present algorithms for Klee's measure problem and 2D convex hulls in this model. Algorithms in the stream-sort model use sorting as a primitive operation. Each pass can either sort the data or make sequential access to the data. As in the multi-pass model, these algorithms can only use sublinear working space and a small (usually a constant) number of passes on the data. We present algorithms for constructing convex hulls and polygon triangulation in this model.
25

Consistency control and memory semantics for persistent objects

Chen, Raymond C. January 1991 (has links)
No description available.
26

Design and analysis of reconfigurable and adaptive cache structures

Bond, Paul Joseph 08 1900 (has links)
No description available.
27

Bicontexts and structural induction

Livesey, Mike January 1987 (has links)
This thesis introduces and explores the notion of bicontext, an order-enriched category equipped with a unary endofunctor of order two called reverse. The purpose is threefold. First, the important categories that arise in Scott-Strachey denotational semantics have this additional structure, where by the constructions used to solve "data-type equations" are both limits and colimits simultaneously. Second, it yields a pleasant "set-theoretic" treatment of algebraic data-types in terms of bicontexts of (1, 1) relations rather than pairs of continuous functions. The theory provides a general way of relating bicontexts which serves to connect these particular ones. Third, the least solutions of data-type equations often have an associated principle of structural induction. Properties in such solutions become arrows in the appropriate bicontext, making the defining functor directly applicable to them. In this way the structural induction can be derived systematically from the functor.
28

Variações e aplicações do algoritmo de Dijkstra / Variants and applications of Dijkstra's algorithms

Neves, Patricia Takaki 08 October 2007 (has links)
Orientador: Orlando Lee / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Computação / Made available in DSpace on 2018-08-09T17:25:07Z (GMT). No. of bitstreams: 1 Neves_PatriciaTakaki_M.pdf: 4451114 bytes, checksum: c4fcf2f5d76f36075020307255c1470c (MD5) Previous issue date: 2007 / Resumo: O problema de encontrar caminhos mínimos em um grafo com pesos nas arestas é considerado fundamental em otimização combinatória. Diversos problemas do mundo real podem ser modelados dessa forma: percurso mais curto/rápido entre duas cidades, transmissão de dados em uma rede de computadores, reconhecimento de voz, segmentação de imagens entre outros. O algoritmo proposto por Dijkstra em 1959 resolve o problema de caminhos mínimos em grafos sem arestas de peso negativo, o que não chega a ser restritivo na maior parte das aplicações. Desde então, o algoritmo tem sido refinado com o uso de estruturas de dados cada vez mais sofisticadas, reduzindo seu tempo de execução de pior caso (ao menos, do ponto de vista teórico). Recentemente, problemas de caminhos mínimos têm aparecido no contexto de Sistemas de Informação Geográfica (SIG). Neste modelo, o usuário faz consultas ao sistema para encontrar o trajeto mais curto (ou rápido) entre dois pontos especificados (problema ponto-a-ponto ou problema P2P). Além disso, pode haver várias consultas. Instâncias neste tipo de modelo são relativamente grandes: o mapa rodoviário dos Estados Unidos tem mais de 20 milhões de vértices (cada vértice representa intersecções de vias). Mesmo as implementações mais sofisticadas do algoritmo de Dijkstra não apresentam um desempenho prático capaz de atender às demandas que esse tipo de modelo requer. A pesquisa recente tem tentado reduzir este gap entre a teoria e a prática. Várias técnicas de aceleração de algoritmos têm sido propostas e implementadas: busca bidirecional, algoritmo A*, alcance (reach), landmarks e muitos outros. Algumas dessas técnicas têm restrições de domínio e outras podem ser usadas em qualquer contexto. Neste trabalho, estudamos algumas variações da versão original do algoritmo de Dijkstra, caracterizadas pelas diferentes estruturas de dados. Implementamos quatro dessas variações e realizamos testes experimentais utilizando os mapas do mundo real. Nosso objetivo foi analisar o desempenho prático dessas. Dedicamos também uma atenção especial ao problema P2P, apresentando algumas das principais técnicas de aceleração / Abstract: The problem of finding shortest paths in a weighted graph is a fundamental one in combinatorial optimization. Several real world problems can be modeled in this way: shortest or fastest tour between two cities, data transmission on a computer network, voice recognition, image segmentation among others. The algorithm proposed by Dijkstra in 1959 solves this problem when the graph has no edge with negative weight, which is not a serious restriction in most applications. Since then, the algorithm has been improved with the use of sophisticated data structures, reducing the worst case running time (at least, from a theoretical viewpoint). Recently shortest path problems has appeared in the context of Geographic Information System (GIS). In this model, the user asks the system to find out the shortest path between two given points (point-to-point problem or P2P problem). Moreover, there can be several queries. Instances in this model are relatively large: the road network map of the United States has more than 20 million vertices (each vertex represents an intersection of two roads). Even the fastest implementations of Dijkstra's algorithm do not have a performance in practice which is satisfactory to meet the requirements of this model. Recent research has tried to reduce this gap between theory and practice. Several speed-up techniques for these algorithms have been proposed and implemented: bidirectional search, algorithm A*, reach, landmarks and many others. Some of them are domain-restricted and others are applicable in any context. In this work, we studied some variants of Dijkstra's algorithm characterized by its different data structures. We have implemented four of those variants and performed experimental tests using real-world maps. Our goal was to analyze their practical performance. We also paid special attention to the P2P problem, and presented some of the main speed-up techniques / Mestrado / Ciência da Computação / Mestre em Ciência da Computação
29

Enhance DBMS capabilities using semantic data modelling approach.

January 1990 (has links)
by Yip Wai Man. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1990. / Bibliography: leaves 132-135. / ABSTRACT / ACKNOWLEDGEMENTS / PART I / Chapter 1 --- OVERVIEW ON SEMANTIC DATA MODELLING APPROACH … --- p.1 / Chapter 2 --- SCOPE OF RESEARCH --- p.4 / Chapter 3 --- CONCEPTUAL STRUCTURE OF SAM* --- p.7 / Chapter 3.1 --- Concepts and Associations --- p.7 / Chapter 3.1.1 --- Membership Association --- p.8 / Chapter 3.1.2 --- Aggregation Association --- p.8 / Chapter 3.1.3 --- Generalization Association --- p.9 / Chapter 3.1.4 --- Interaction Association --- p.10 / Chapter 3.1.5 --- Composition Association --- p.11 / Chapter 3.1.6 --- Cross-Product Association --- p.12 / Chapter 3.1.7 --- Summary Association --- p.13 / Chapter 3.2 --- An Example --- p.14 / Chapter 3.3 --- Occurrences --- p.15 / PART II / Chapter 4 --- SYSTEM OVERVIEW --- p.17 / Chapter 4.1 --- System Objectives --- p.17 / Chapter 4.1.1 --- Data Level --- p.17 / Chapter 4.1.2 --- Meta-Data Level --- p.18 / Chapter 4.2 --- System Characteristics --- p.19 / Chapter 4.3 --- Design Considerations --- p.20 / Chapter 5 --- IMPLEMENTATION CONSIDERATIONS --- p.23 / Chapter 5.1 --- Introduction --- p.23 / Chapter 5.2 --- Data Definition Language for Schema --- p.24 / Chapter 5.3 --- Construction of Directed Acyclic Graph --- p.27 / Chapter 5.4 --- Query Manipulation Language --- p.28 / Chapter 5.4.1 --- Semantic Manipulation Language --- p.29 / Chapter 5.4.1.1 --- Locate Concepts --- p.30 / Chapter 5.4.1.2 --- Retrieve Information About Concepts --- p.30 / Chapter 5.4.1.3 --- Find a Path Between Two Concepts --- p.31 / Chapter 5.4.2 --- Occurrence Manipulation Language --- p.32 / Chapter 5.5 --- Examples --- p.35 / Chapter 6 --- RESULTS AND DISCUSSIONS --- p.41 / Chapter 6.1 --- Allow Non-Homogeneity of Facts about Entities --- p.41 / Chapter 6.2 --- Field Name is Information --- p.42 / Chapter 6.3 --- Description of Group of Information --- p.43 / Chapter 6.4 --- Explicitly Description of Interaction --- p.43 / Chapter 6.5 --- Information about Entities --- p.44 / Chapter 6.6 --- Automatically Joining Tables --- p.45 / Chapter 6.7 --- Automatically Union Tables --- p.45 / Chapter 6.8 --- Automatically Select Tables --- p.46 / Chapter 6.9 --- Ambiguity --- p.47 / Chapter 6.10 --- Normalization --- p.47 / Chapter 6.11 --- Update --- p.50 / PART III / Chapter 7 --- SCHEMA VERIFICATION --- p.55 / Chapter 7.1 --- Introduction --- p.55 / Chapter 7.2 --- Need of Schema Verification --- p.57 / Chapter 7.3 --- Integrity Constraint Handling Vs Schema Verification --- p.58 / Chapter 8 --- AUTOMATIC THEOREM PROVING --- p.60 / Chapter 8.1 --- Overview --- p.60 / Chapter 8.2 --- A Discussion on Some Automatic Theorem Proving Methods --- p.61 / Chapter 8.2.1 --- Resolution --- p.61 / Chapter 8.2.2 --- Natural Deduction --- p.63 / Chapter 8.2.3 --- Tableau Proof Methods --- p.65 / Chapter 8.2.4 --- Connection Method --- p.67 / Chapter 8.3 --- Comparison of Automatic Theorem Proving Methods --- p.70 / Chapter 8.3.1 --- Proof Procedure --- p.70 / Chapter 8.3.2 --- Overhead --- p.70 / Chapter 8.3.3 --- Unification --- p.71 / Chapter 8.3.4 --- Heuristics --- p.72 / Chapter 8.3.5 --- Getting Lost --- p.73 / Chapter 8.4 --- The Choice of Tool for Schema Verification --- p.73 / Chapter 9 --- IMPROVEMENT OF CONNECTION METHOD --- p.77 / Chapter 9.1 --- Motivation of Improving Connection Method --- p.77 / Chapter 9.2 --- Redundancy Handled by the Original Algorithm --- p.78 / Chapter 9.3 --- Design Philosophy of the Improved Version --- p.82 / Chapter 9.4 --- Primary Connection Method Algorithm --- p.83 / Chapter 9.5 --- AND/OR Connection Graph --- p.89 / Chapter 9.6 --- Graph Traversal Procedure --- p.91 / Chapter 9.7 --- Elimination Redundancy Using AND/OR Connection Graph --- p.94 / Chapter 9.8 --- Further Improvement on Graph Traversal --- p.96 / Chapter 9.9 --- Comparison with Original Connection Method Algorithm --- p.97 / Chapter 9.10 --- Application of Connection Method to Schema Verification --- p.98 / Chapter 9.10.1 --- Express Constraint in Well Formed Formula --- p.98 / Chapter 9.10.2 --- Convert Formula into Negation Normal Form --- p.101 / Chapter 9.10.3 --- Verification --- p.101 / PART IV / Chapter 10 --- FURTHER DEVELOPMENT --- p.103 / Chapter 10.1 --- Intelligent Front-End --- p.103 / Chapter 10.2 --- On Connection Method --- p.104 / Chapter 10.3 --- Many-Sorted Calculus --- p.104 / Chapter 11 --- CONCLUSION --- p.107 / APPENDICES / Chapter A --- COMPARISON OF SEMANTIC DATA MODELS --- p.110 / Chapter B --- CONSTRUCTION OP OCCURRENCES --- p.111 / Chapter C --- SYNTAX OF DDL FOR THE SCHEMA --- p.113 / Chapter D --- SYNTAX OF SEMANTIC MANIPULATION LANGUAGE --- p.116 / Chapter E --- TESTING SCHEMA FOR FUND INVESTMENT DBMS --- p.118 / Chapter F --- TESTING SCHEMA FOR STOCK INVESTMENT DBMS --- p.121 / Chapter G --- CONNECTION METHOD --- p.124 / Chapter H --- COMPARISON BETWEEN RESOLUTION AND CONNECTION METHOD --- p.128 / REFERENCES --- p.132
30

The multi-lingual database system : a paradigm and test-bed for the investigation of data-model transformations and data-model semantics /

Demurjian, Steven Arthur January 1987 (has links)
No description available.

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