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Palestra: "Multimedia Access control, XML Similarity and Query rewriting"
Palestra do Prof. Dr. Richard CHBEIR, na Série de Seminários 2008 da Pós-Graduação dia 25/08/2008, às 14h, Sala 316 - IC 3.
| What | Palestra |
|---|---|
| When |
25/08/2008 from 14:00 to 16:00 |
| Where | Sala 316 - IC 3 |
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The talk will oversee three research studies: Multimedia Access control, XML Similarity and Query rewriting. Multimedia Access control The rapid development of information systems has lead in many ways to the definition of advanced authorization and access control models. Recent models have considered context (such as time, location, age, etc.) as key issue to allow flexible and dynamic policy specification. However, these models are application-dependent, text-based, complex to manage, and insufficient to deny unauthorized access in several cases. Multimedia-based context (user surrounding snapshot, his moves and gesture, etc.) reveals interesting information which is considered of complimentary importance to textual-based context and should be considered in several scenarios while defining access control conditions. In the first part of the talk, we present some existing techniques and show how to extend current models with a Multimedia Access Control Model (MACM) based on: flexible multimedia data description, complex and multi-criteria conditions, and an uncertainty resolver able to reduce potential risk related to the use of multimedia data and similarity functions. XML Similarity Similarity serves as an organization principle by which individuals classify objects, form concepts and make generalizations. It plays a central role in various research areas, particularly in the XML field where similarity evaluation of XML data has been receiving a lot of attention. In essence, W3Cs XML (eXtensible Mark-up Language) has recently gained unparalleled importance as a fundamental standard for efficient data management and exchange. Information destined to be broadcasted over the web is henceforth represented using XML, in order to guaranty its interoperability. The use of XML covers data representation and storage (e.g. complex multimedia objects), database information interchange, data filtering, as well as web services interaction. Owing to the ever-increasing abundant use of XML especially on the web, XML-based similarity/comparison becomes a central issue, specifically in the information retrieval (IR) and database (DB) communities, its applications ranging over: * Version control, change management and data warehousing (finding, scoring and browsing changes between different versions of a document, support of temporal queries and index maintenance), * Semi-structured data integration (measuring the similarity between XML documents in order to undertake the integration of corresponding data sources), * Classification/clustering of XML documents gathered from the web against a set of DTDs declared in an XML database (just as schemas are necessary in traditional DBMS for the provision of efficient storage, retrieval, protection and indexing facilities, the same is true for DTDs and XML repositories), * XML query systems (finding and ranking results according to their similarity in order to retrieve the best results possible). In this second part of the talk, we give an overview of existing research related to XML similarity, in both its AI dynamic programming (ED-based approaches) and Information Retrieval fields. We show how: * Most approaches in the ED literature focus exclusively on the structure of documents, ignoring the semantics involved. * Most approaches ignore several XML similarity cases where the corresponding edit distance outcome is inaccurate. We present our proposal and prototype aiming at both combining structural similarity computations with semantic similarity assessment, in an XML (structured data) context, and providing an improved fine-grained method for comparing heterogeneous XML documents. Query Rewriting A multimedia query can be multicriteria and based on several heterogeneous features (colors, textures, etc.). Two main parameters make multimedia query processing a difficult task: 1-the imprecise user request due to the user uncertainty or to the vagueness of his need, 2-describing a multimedia object depends on each person and on each moment. This is why several methods are provided in the literature to assist the user during (and/or after) query writing. Some attempts in information retrieval and recently in web semantic aim to rewrite the initial query using relaxing and enriching techniques in order to relate the query content to the database (or corpus) content. In spite of the existence of many proposals for textual and metadata reformulation during retrieval process, a few of them consider multimedia queries. In the last part of the talk, we briefly present some exiting techniques and pin down their drawbacks when addressing multimedia queries. We also present a new method able to rewrite multicriteria queries while including the user preferences. Biography Dr. Richard CHBEIR received his PhD in Computer Science from the University of INSA, FRANCE. Actually, he is Associate Professor of Computer Science in the University of Bourgogne, France. His current research interests are in the areas of multimedia information retrieval, distributed multimedia database management, spatio-temporal relations, access control models, Bioinformatics, and the development and the integration of information systems. He is Chair of ACM SIGAPP French Chapter, and member of several conference and journal Program Committees (EuroPar, IEEE ISSPIT, ACM ASIIS, ICIT, ACM SWS, etc.). He published in several international journals (IEEE Transactions on SMC, Information Systems, Journal on Data Semantics, Journal of Methods of Information in medicine, etc.), and conferences (ER, EDBT, ACM Multimedia, IEEE SITIS, ACM SAC, Visual, SOFSEM, FLAIRS, IEEE ICME, etc.).
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