The Strudel system applies concepts from database management systems to the process of building Web sites. Strudel's key idea is separating the management of the site's data, the creation and management of the site's structure, and the visual presentation of the site's pages. First, the site builder creates a uniform model of all data available at the site. Second, the builder uses this model to declaratively define the Web site's structure by applying a "site-definition query" to the underlying data. The result of evaluating this query is a "site graph", which represents both the site's content and structure. Third, the builder specifies the visual presentation of pages in Strudel's HTML-template language. The data model underlying Strudel is a semi-structured model of labeled directed graphs. We describe Strudel's key characteristics, report on our experiences using Strudel, and present the technical problems that arose from our experience. We describe our experience constructing sev...

The creation of a complex web site is a thorny problem in user interface design. In IJCAI '97, we challenged the AI community to address this problem by creating adaptive web sites: sites that automatically improve their organization and presentation by mining visitor access data collected in Web server logs. In this paper weintroduce our own approach to this broad challenge. Specifically, we investigate the problem of index page synthesis --- the automatic creation of pages that facilitate a visitor's navigation of a Web site. First, we formalize this problem as a clustering problem and introduce a novel approach to clustering, which we call cluster mining: Instead of attempting to partition the entire data space into disjoint clusters, we search for a small number of cohesive (and possibly overlapping) clusters. Next, we present PageGather, a cluster mining algorithm that takes Web server logs as input and outputs the contents of candidate index pages. Finally, we show experime...

The management of semistructured data has recently received significant attention because of the need of several applications to model and query large volumes of irregular data. This paper considers the problem of query containment for a query language over semistructured data, StruQL0 , that contains the essential feature common to all such languages, namely the ability to specify regular path expressions over the data. We show here that containment of StruQL0 queries is decidable. First, we give a semantic criterion for StruQL0 query containment: we show that it suffices to check containment on only finitely many canonical databases. Second, we give a syntactic criteria for query containment, based on a notion of query mappings, which extends containment mappings for conjunctive queries. Third, we consider a certain fragment of StruQL0 , obtained by imposing restrictions on the regular path expressions, and show that query containment for this fragment of StruQL0 is NP complete. 1 ...

XML is the W3C standard document format for writing and exchanging information on the Web. RDF is the W3C standard model for describing the semantics and reasoning about information on the Web. Unfortunately, RDF and XML---although very close to each other---are based on two different paradigms. We argue that in order to lead the Semantic Web to its full potential, the syntax and the semantics of information needs to work together. To this end, we develop a model theory for the XML XQuery 1.0 and XPath 2.0 Data Model, which provides a unified model for both XML and RDF. This unified model can serve as the basis for Web applications that deal with both data and semantics. We illustrate the use of this model on a concrete information integration scenario. Our approach enables each side of the fence to benefit from the other, notably, we show how the RDF world can take advantage of XML query languages, and how the XML world can take advantage of the reasoning capabilities available for RDF.

The necessity for ontology building, annotating, integrating and learning tools is uncontested. However, the sole representation of knowledge and information is not enough. Human information consumers and web agents have to use and query ontologies and the resources committed to them, thus the need for ontology storage and querying tools arises. However, the context of storing and querying

The need for descriptive information, i.e., metadata, about Web resources has been recognized in several application contexts (e.g., digital libraries, infomediaries, portals, etc.). The Resource Description Framework (RDF) aims at facilitating the creation and exchange of metadata, as any other Web data. In particular, the definition of schema vocabularies enables the interpretation of RDF descriptions across several communities.

. The need for descriptive information, i.e., metadata, about Web resources has been recognized in several application contexts (e.g., digital libraries, portals). The Resource Description Framework (RDF) aims at facilitating the creation and exchange of metadata, as directed labeled graphs serialized in XML. In particular, the definition of schema vocabularies enables the interpretation of semistructured RDF descriptions using taxonomies of node and edge labels. In this paper, we propose (i) a formal model capturing RDF schema constructs; (ii) a declarative query language featuring generalized path expressions for taxonomies of labels (iii) a metadata management architecture for efficient storage and querying of RDF descriptions and schemas. 1 Introduction Metadata are widely used in order to fully exploit information resources (e.g., sites, documents, data, etc.) available on the WWW [13]. Indeed, metadata permit the description of the content and/or structure of WWW reso...

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XML is the W3C standard document format for writing and exchanging information on the Web. RDF is the W3C standard model for describing the semantics and reasoning about information on the Web. Unfortunately, RDF and XML -- although very close to each other -- are based on two different paradigms. We argue that in order to lead the Semantic Web to its full potential, the syntax and the semantics of information need to work together. To this end, we develop a model theory for the XML XQuery 1.0 and XPath 2.0 Data Model, which provides a unified model for both XML and RDF. This unified model can serve as the basis for Web applications that deal with both data and semantics. We illustrate the use of this model on a concrete information integration scenario. Our approach enables each side of the fence to benefit from the other, notably, we show how the RDF world can take advantage of XML Schema description and XML query languages, and how the XML world can take advantage of the reasoning capabilities available for RDF. Our approach can also serve as a foundation for the next layer of the Semantic Web, the ontology layer, and we present a layering of an ontology language on top of our approach.

The creation of a complex web site is a thorny problem in user interface design. In IJCAI '97, wechallenged the AI community to address this problem by creating adaptive web sites: sites that automatically improve their organization and presentation by mining visitor access data collected in Web server logs. In this paper weintroduce our own approachtothisbroadchallenge. Specifically, weinvestigate the problem of index page synthesis --- the automatic creation of pages that facilitate a visitor's navigation of a Web site. First, we formalize this problem as a clustering problem and introduce a novel approach to clustering, whichwe call cluster mining: Instead of attempting to partition the entire data space into disjoint clusters, we search forasmallnumber of cohesive (and possibly overlapping) clusters. Next, we presentPageGather, a cluster mining algorithm that takes Web server logs as input and outputs the contents of candidate index pages. Finally, weshow experime...