The area of databases has evolved rapidly in recent years in response to new requirements of advanced applications. Databases must now handle a wide variety of data types, ranging from relational to textual, sequential, spatial, audio, etc. Data is increasingly heterogeneous and globally distributed among a variety of sources. And, applications increasingly require functionalities such as activeness. These developments pose new challenges to the design and implementation of query and update languages, and raise fundamentally novel issues that require developing specific, principled approaches. The aim of the proposed research is to develop such approaches to querying and updating advanced database systems, focusing primarily on the logical level: languages and computational aspects. The results of the project are expected to yield better understanding of basic problems facing current database systems, and will provide tools to facilitate the principled design and implementation of query and update languages. They will contribute to technological advances in several fast-developing areas: representing and querying information on the Web, applications requiring activeness capabilities (such as electronic commerce), and applications handling heterogeneous data (such as spatial databases). http://www-cse.ucsd.edu/users/vianu/IIS-9802288.html
