Thesis (Ph. D.)--Ohio University, June, 1999. / Title from PDF t.p.

Thesis (M.S. in Computer Science)--Naval Postgraduate School, March 2005. / Thesis Advisor(s): Thomas W. Otani. Includes bibliographical references (p. 173). Also available online.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 127-136). Also available in electronic version.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: continuous queries; moving objects. Includes bibliographical references (p.102-110).

Thesis (M.S.)--Worcester Polytechnic Institute. / Keywords: XML, Query Re-Writing, View Maintenance, Query Containment. Includes bibliographical references. (p.108-111)

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 137-144).

We propose a balanced tree structure overlay on a peer-to-peer network capable of supporting both exact queries and range queries efficiently. In spite of the tree structure causing distinctions to be made between nodes at different levels in the tree, we show that the load at each node is approximately equal. In spite of the tree structure providing precisely one path between any pair of nodes, we show that sideways routing tables maintained at each node provide sufficient fault tolerance to permit efficient repair. Specifically, in a network with N nodes, we guarantee that both exact queries and range queries can be answered in O(logN) steps and also that update operations (to both data and network) have an amortized cost of O(logN). An experimental assessment validates the practicality of our proposal. / Singapore-MIT Alliance (SMA)

Στα πλαίσια της παρούσας διπλωματικής εργασίας, ασχολούμαστε με την αυτόματη κατηγοριοποίηση των αποτελεσμάτων των αναζητήσεων στον Παγκόσμιο Ιστό. Αρχικά, ορίζουμε τα χαρακτηριστικά των σελίδων που είναι κατάλληλα για κατηγοριοποίηση με βάση την πρόθεση του χρήστη. Έπειτα, με χρήση μεθόδων μείωσης της διαστατικότητας επιλέγουμε τα πιο αντιπροσωπευτικά από τα χαρακτηριστικά αυτά και αξιολογούμε την απόδοση διάφορων αλγορίθμων κατηγοριοποίησης. Ακολούθως, επιλέγουμε τον αλγόριθμο κατηγοριοποίησης που βασίζεται στα επιλεγμένα χαρακτηριστικά και επιτυγχάνει την καλύτερη απόδοση. Εφαρμόζοντας τον αλγόριθμο, κατηγοριοποιούμε τα αποτελέσματα των αναζητήσεων στον Παγκόσμιο Ιστό. Τέλος, προτείνουμε μια μέθοδο εξαγωγής όρων από τα κατηγοριοποιημένα αποτελέσματα και επαναδιατύπωσης του ερωτήματος με βάση τον σκοπό αναζήτησης του χρήστη. / In this thesis, we tackle the problem of automatic classification of search results in Web environment. First, we define web pages features that are convenient for classification based on the user’s intent. Next, we use dimensionality reduction techniques to choose the most representative features and we evaluate different classification algorithms. We choose the most efficient classification algorithm based on chosen features and by using it, we classify the results retrieved from web searches. In the end, we propose a method to extract terms from the classified results and to reformulate the query based on user intent.

Uma das principais tarefas de Recuperação de Informações é encontrar documentos que sejam relevantes a uma consulta. Esta tarefa é difícil porque, em muitos casos os termos de busca escolhidos pelo usuário são diferentes dos termos utilizados pelos autores dos documentos. Ao longo dos anos, várias abordagens foram propostas para lidar com este problema. Uma das técnicas mais utilizadas, com o objetivo de expandir o número de documentos relevantes recuperados é a Expansão de Consultas, que consiste em expandir a consulta com a adição de termos relacionados. Este trabalho propõe um método que utiliza o modelo de Cell Assemblies para a expansão da consulta. Cell Assemblies são grupos de neurônios conectados, com padrões de disparo, que permitem que a atividade persista mesmo após a remoção dos estímulos externos. A modificação das sinapses entre os neurônios é feita através de regras de aprendizagem Hebbiana. Neste trabalho, o modelo Cell Assemblies foi adaptado a fim de aprender os relacionamentos entre os termos de uma coleção de documentos. Esses relacionamentos são utilizados para expandir a consulta original com termos relacionados. A avaliação experimental sobre uma coleção de testes padrão em Recuperação de Informações mostrou que algumas consultas melhoraram significativamente seus resultados com a técnica proposta. / One of the main tasks in Information Retrieval is to match a user query to the documents that are relevant for it. This matching is challenging because in many cases the keywords the user chooses will be different from the words the authors of the relevant documents have used. Throughout the years, many approaches have been proposed to deal with this problem. One of the most popular consists in expanding the query with related terms with the goal of retrieving more relevant documents. In this work, we propose a new method in which a Cell Assembly model is applied for query expansion. Cell Assemblies are reverberating circuits of neurons that can persist long beyond the initial stimulus has ceased. They learn through Hebbian Learning rules and have been used to simulate the formation and the usage of human concepts. We adapted the Cell Assembly model to learn relationships between the terms in a document collection. These relationships are then used to augment the original queries. Our experiments use standard Information Retrieval test collections and show that some queries significantly improved their results with the proposed technique.

O problema da integração de dados (fragmentação de dados, decomposição de consultas) tem sido largamente estudado na literatura, mas a estrutura hierárquica inerente do modelo XML apresenta problemas que são específicos deste modelo de dados. Cada relacionamento conceitual muitos-para-muitos deve ser mapeado para uma estrutura hierárquica específica em XML. Diferentes fontes XML podem implementar o mesmo relacionamento conceitual muitos-para-muitos de diferentes maneiras. Na abordagem proposta neste trabalho, o problema de integra»c~ao de fontes de dados XML é dividido em dois problemas: (1) naquele da fragmentação de um modelo global do tipo grafo (ex., um modelo ER) em diversos modelos locais do tipo grafo representando conceitualmente fontes de dados e (2) naquele do ma- peamento de um modelo local do tipo grafo em um esquema hierárquico XML. Este trabalho apresenta um conjunto de operadores especificamente projetados para esta abordagem, assim como um mecanismo de decomposi»c~ao que permite que uma con- sulta especificada em um nível conceitual seja decomposta em uma consulta XQuery especificada no nível XML. Como linguagem de consulta para o nível conceitual, é adotado o CXPath (Conceptual XPath), uma linguagem de consulta proposta em um trabalho anterior. / The problem of data integration (query decomposition, data fragmentation) has been widely studied in literature, but the inherent hierarchical nature of XML data presents problems that are specific to this data model. Each many-to-many con- ceptual relationship must be mapped to a specific hierarchical structure in XML. Di®erent XML sources may implement the same many-to-many conceptual rela- tionship in di®erent ways. In our approach the problem of integration of XML data sources is decomposed in two problems: (1) that of fragmentation of a global graph-like model (e.g., an ER model) into several local graph-like models conceptu- ally representing data sources and (2) that of mapping the local graph-like model into an XML tree-like schema. This work presents a set of fragmentation operators specifically designed for our approach, as well as a query decomposition mechanism that allows a query stated at the conceptual level to be decomposed into an XQuery statement at the XML level. As the query language at the conceptual level, we adopt CXPath (conceptual XPath) a query language we have defined in previous work.