This volume contains the papers selected for the third International Conference on Database Theory, ICDT'90. The papers describe original ideas and new results on the foundations of databases, knowledge bases, object-oriented databases, relational theory, transaction management, data structures and deductive databases.

Finite-model theory—a personal perspective.- Playing games with objects.- Representing object identity in a pure functional language.- A class abstraction for a hierarchical type system.- Algebraic optimization of object-oriented query languages.- A relational object model.- Maintaining bounded disorder files in multiprocessor multi-disk environments.- An evaluation model for clustering strategies in the O2 object-oriented database system.- Efficient algorithms for managing the history of evolving databases.- Logic and Databases: An assessment.- A closed form for datalog queries with integer order.- On the expressive power of the relational calculus with arithmetic constraints.- Conjectures and refutations in database design and dependency theory.- A theory of specialization constraints for complex objects.- Removing redundancy and updating databases.- Improving the concurrency of integrity checks and write operations.- A flexible and adaptable tool kit approach for concurrency control in non standard database systems.- A comparative analysis of two-phase-commit protocols.- Efficient voting protocols with witnesses.- Voting and relocation strategies preserving consistency among replicated files.- Well!: An evaluation procedure for all logic programs.- Beginnings of a theory of general database completions.- Recursively indefinite databases.- Low complexity aggregation in graphlog and Datalog.- Deciding boundedness for uniformly connected Datalog programs.- The Revised Gärdenfors postulates and update semantics.- Foundations of canonical update support for closed database views.- Drawing updates from derivations.- Optimization of a subclass of conjunctive queries.- Complex transitive closure queries on a fragmented graph.- Multiple SIP strategies and bottom-upadorning in logic query optimization.- On estimating the size of projections.- Static estimation of query sizes in horn programs.