Invited Presentation -- The Semijoin Algebra -- Regular Papers -- Equational Constraint Solving Via a Restricted Form of Universal Quantification -- Modeling the Evolution of Objects in Temporal Information Systems -- Controlled Query Evaluation with Open Queries for a Decidable Relational Submodel -- Iterative Modification and Incremental Evaluation of Preference Queries -- On the Number of Independent Functional Dependencies -- Arity and Alternation: A Proper Hierarchy in Higher Order Logics -- Solving Abduction by Computing Joint Explanations: Logic Programming Formalization, Applications to P2P Data Integration, and Complexity Results -- The Nested List Normal Form for Functional and Multivalued Dependencies -- Axiomatising Functional Dependencies for XML with Frequencies -- Guarded Open Answer Set Programming with Generalized Literals -- Reasoning Support for Expressive Ontology Languages Using a Theorem Prover -- Consistency Checking Algorithms for Restricted UML Class Diagrams -- Some Contributions to the Minimum Representation Problem of Key Systems -- On Multivalued Dependencies in Fixed and Undetermined Universes -- Preference-Based Query Tuning Through Refinement/Enlargement in a Formal Context -- Processing Ranked Queries with the Minimum Space -- Hybrid Minimal Spanning Tree and Mixture of Gaussians Based Clustering Algorithm.