Abstract. The first step in finding an efficient way to solve any difficult problem is making a complete, possibly formal, problem specification. This paper introduces a formal specification for the problem of semantic XML schema matching. Semantic schema matching has been extensively researched, and many matching systems have been developed. However, formal specifications of problems being solved by these systems do not exist, or are partial. In this paper, we analyze the problem of semantic schema matching, identify its main components and deliver a formal specification based on the constraint optimization problem formalism. Throughout the paper, we consider the schema matching problem as encountered in the context of a large scale XML schema matching application. 1

Today, information retrieval and integration has assumed a totally different, complex connotation than what it used to be. The advent of the Internet, the proliferation of information sources, the presence of structured, semi-structured, and unstructured data- all of have added new dimensions to the problem of information retrieval and integration as known earlier. From the time of distributed databases leading to heterogeneous, federated, and multi-databases, retrieval and integration of heterogeneous information has been an important problem for which a complete solution has eluded researchers for a number of decades. Techniques such as global schemas, schema integration, dealing with multiple schemas, domain specific wrappers, and global transactions have produced significant steps but never reached the stage of maturity for large scale deployment and usage. Currently, the problem is even more complicated as repositories exist in various formats (HTML, XML, Web Databases with query-interfaces,...) and schemas, and both the content and the structure are changing autonomously. In this survey paper, we describe the general problem of information retrieval and integration and discuss the challenges that need to be addressed to deal with the general problem of information retrieval

Abstract. As XML technologies have undoubtedly become a standard for data representation, it is inevitable to provide efficient implementations of W3C recommendations. A possible optimization of particular types of techniques can be found in exploitation of similarity of XML data and/or matching of XML patterns. In this paper we provide an overview and classification of such techniques from various points of view. We also briefly describe the best known representatives of particular ideas and we discuss their key advantages and disadvantages. The text should serve as a good starting point for proposing an appropriate similarity-based optimization. 1

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