First Year Report on Work Package 1

Objective of the WP. The key objectives of this work package are: 1. to develop a software library that contains tools for handling XML schemas, and which is suitable for testing the models and tools developed in the project; 2. to expand the focus of XML schema formalisms from the structure-centric to a data-oriented approach to XML and to develop models for handling data in XML documents; 3. to develop models and tools for the management of distributed repositories of XML documents and schemas stored across multiple sites; and 4. to develop models and methods for the management of XML repositories in the presence of other data models. The four objectives correspond to the four tasks T1.1 Developing a foundational Schema Software Library T1.2 Reasoning about models and constraints involving data values T1.3 Management of XML repositories T1.4 Combining multiple data models Main results. The key achievements of the year are in the development of the software library, reasoning about models and constraints involving data, and schema management for large, distributed documents. The most spectacular results have been achieved in task T1.2. The understanding of the interplay between structural and data-oriented constraints has been improved considerably in a series of published research papers. The single most striking achievement is the decidability of an important fragment of XPath in the presence of value comparisons [6]. This is an important step toward the goals of task T1.2 as it tells us that, in principle, we can reason about the most frequently used part of XPath