This book constitutes the refereed proceedings of the 20th International Conference on Database and Expert Systems Applications, DEXA 2009, held in Linz, Austria, in August/September 2009. database and information system architecture, performance and security; and database and information system architecture and performance.

Invited Talk.- Management of Information Supporting Collaborative Networks.- XML and Databases I.- A Low-Storage-Consumption XML Labeling Method for Efficient Structural Information Extraction.- Inclusion Dependencies in XML: Extending Relational Semantics.- The Real Performance Drivers behind XML Lock Protocols.- XML and Databases II.- XTaGe: A Flexible Generation System for Complex XML Collections.- Utilizing XML Clustering for Efficient XML Data Management on P2P Networks.- On the Termination Problem for Declarative XML Message Processing.- Web, Semantics and Ontologies I.- Consistency Checking for Workflows with an Ontology-Based Data Perspective.- Conceptual and Spatial Footprints for Complex Systems Analysis: Application to the Semantic Web.- Automatic Extraction of Ontologies Wrapping Relational Data Sources.- Temporal, Spatial, and High Dimensional Databases (Short Papers).- A Query Cache Tool for Optimizing Repeatable and Parallel OLAP Queries.- Efficient Map Portrayal Using a General-Purpose Query Language.- On Low Distortion Embeddings of Statistical Distance Measures into Low Dimensional Spaces.- Real-Time Traffic Flow Statistical Analysis Based on Network-Constrained Moving Object Trajectories.- Invited Talk.- Data Management for Federated Biobanks.- Web, Semantics and Ontologies II.- Peer-to-Peer Semantic Wikis.- VisiNav: Visual Web Data Search and Navigation.- Diagnosing and Measuring Incompatibilities between Pairs of Services.- Database and Information System Architecture, Performance and Security (Short Papers).- Scaling-Up and Speeding-Up Video Analytics Inside Database Engine.- Experimental Evaluation of Processing Time for the Synchronization of XML-Based Business Objects.- SimulPh.D.: A Physical Design Simulator Tool.- Protecting Database Centric Web Services against SQL/XPath Injection Attacks.- Reasoning on Weighted Delegatable Authorizations.- Web, Semantics and Ontologies III.- Annotating Atomic Components of Papers in Digital Libraries: The Semantic and Social Web Heading towards a Living Document Supporting eSciences.- Web Navigation Sequences Automation in Modern Websites.- Supporting Personal Semantic Annotations in P2P Semantic Wikis.- XML and Databases III (Short Papers).- OrdPathX: Supporting Two Dimensions of Node Insertion in XML Data.- XQSuggest: An Interactive XML Keyword Search System.- A Prüfer Based Approach to Process Top-k Queries in XML.- Bottom-Up Evaluation of Twig Join Pattern Queries in XML Document Databases.- Query Rewriting Rules for Versioned XML Documents.- Querying XML Data with SPARQL.- Query Processing and Optimization I.- Progressive Evaluation of XML Queries for Online Aggregation and Progress Indicator.- Dynamic Query Processing for P2P Data Services in the Cloud.- A Novel Air Index Scheme for Twig Queries in On-Demand XML Data Broadcast.- Semantic Web and Ontologies IV (Short Papers).- Semantic Fields: Finding Ontology Relationships.- Complete OWL-DL Reasoning Using Relational Databases.- FRESG: A Kind of Fuzzy Description Logic Reasoner.- Extracting Related Words from Anchor Text Clusters by Focusing on the Page Designer’s Intention.- Invited Talk.- Evolution of Query Optimization Methods: From Centralized Database Systems to Data Grid Systems.- Query Processing and Optimization II.- Reaching the Top of the Skyline: An Efficient Indexed Algorithm for Top-k Skyline Queries.- Energy Efficient and Progressive Strategy for Processing Skyline Queries on Air.- RoK: Roll-Up with the K-Means Clustering Method for Recommending OLAP Queries.- Query Processing and Optimization III.-On Index-Free Similarity Search in Metric Spaces.- An Approximation Algorithm for Optimizing Multiple Path Tracking Queries over Sensor Data Streams.- Data and Information Integration and Quality.- A Versatile Record Linkage Method by Term Matching Model Using CRF.- On-the-Fly Integration and Ad Hoc Querying of Life Sciences Databases Using LifeDB.- Analyses and Validation of Conditional Dependencies with Built-in Predicates.- Data Mining and Knowledge Extraction (Short Papers).- Discovering Sentinel Rules for Business Intelligence.- Discovering Trends and Relationships among Rules.- Incremental Ontology-Based Extraction and Alignment in Semi-structured Documents.- Tags4Tags: Using Tagging to Consolidate Tags.- Data and Information Streams.- Detecting Projected Outliers in High-Dimensional Data Streams.- Significance-Based Failure and Interference Detection in Data Streams.- Incremental and Adaptive Clustering Stream Data over Sliding Window.- Data Mining Algorithms.- Alignment of Noisy and Uniformly Scaled Time Series.- Extracting Decision Correlation Rules.- Maintaining the Dominant Representatives on Data Streams.- Data and Information Modelling.- Modeling Complex Relationships.- Intuitive Visualization-Oriented Metamodeling.- Information Retrieval and Database Systems (Short Papers).- PISA: Federated Search in P2P Networks with Uncooperative Peers.- Analysis of News Agencies’ Descriptive Features of People and Organizations.- Analyzing Document Retrievability in Patent Retrieval Settings.- Classifying Web Pages by Using Knowledge Bases for Entity Retrieval.- Terminology Extraction from Log Files.- Database and Information System Architecture and Performance.- Evaluating Non-In-Place Update Techniques for Flash-Based Transaction Processing Systems.- A RelationalEncoding of a Conceptual Model with Multiple Temporal Dimensions.- Three Approximation Algorithms for Energy-Efficient Query Dissemination in Sensor Database System.- Query Processing and Optimization IV (Short Papers).- Top-k Answers to Fuzzy XPath Queries.- Deciding Query Entailment in Fuzzy Description Logic Knowledge Bases.- An Optimization Technique for Multiple Continuous Multiple Joins over Data Streams.- Top-k Queries with Contextual Fuzzy Preferences.- Reranking and Classifying Search Results Exhaustively Based on Edit-and-Propagate Operations.

This book constitutes the refereed proceedings of the 20th International Conference on Database and Expert Systems Applications, DEXA 2009, held in Linz, Austria, in August/September 2009. The 35 revised full papers and 35 short papers  presented were carefully reviewed and selected from 202 submissions. The papers are organized in topical sections on XML and databases; Web, semantics and ontologies; temporal, spatial, and high dimensional databases; database and information system architecture, performance and security; query processing and optimisation; data and information integration and quality; data and information streams; data mining algorithms; data and information modelling; information retrieval and database systems; and database and information system architecture and performance.