Chutiporn Anutariya

A data model for XML databases

In the proposed data model for XML databases, an XML element is directly represented as a ground (variable-free) XML expression—a generalization of an XML element by incorporation of variables for representation of implicit information and enhancement of its expressive power—while a collection of XML documents as a set of ground expressions, each describing an XML element in the documents. Axioms and relationships among elements in the collection as well as structural and integrity constraints are formalized as XML clauses. An XML database, consisting of: (i) a document collection (or an extensional database), (ii) a set of axioms and relationships (or an intensional database), (iii) a set of integrity constraints, is therefore modeled as an XML declarative description comprising a set of ground XML expressions and XML clauses. Its semantics is a set of ground XML expressions, which are explicitly described by the extensional database or implicitly derived from the database, based on the defined intensional database, and satisfy all the specified set of constraints. Thus, selective and complex queries, formulated as sets of XML clauses, about information satisfying specific criteria and possibly implicit in the database, become expressible and computable. The model thereby serves as an effective and well-founded XML database management framework with succinct representational and operational uniformity, reasoning capabilities as well as complex and deductive query supports.

Towards a Foundation for XML Document Databases

This paper develops a theoretical framework for modeling and managing XML documents by employment of Declarative Description (DD) theory. In the framework, the definition of an XML element is formally extended by incorporation of variables in order to represent inherent implicit information and enhance its expressive power. An XML document - a set of XML elements - is simply modeled as an XML declarative description which consists of object descriptions, representing XML elements in the document, and relationship descriptions, specifying relationships among the elements as well as integrity constraints. DTDs and complex queries can also be expressed and evaluated.

A Data Model for XML Databases

In the proposed data model for XML databases, an XML element is directly represented as a ground (variable-free) XML expression--a generalization of an XML element by incorporation of variables for representation of implicit information and enhancement of its expressive power--while a collection of XML documents as a set of ground expressions, each describing an XML element in the documents. Relationships among elements in the collection as well as integrity constraints are formalized as XML clauses. An XML database, consisting of: (i) a document collection (or an extensional database), (ii) a set of relationships (or an intensional database) and (iii) a set of integrity constraints, is therefore modeled as an XML declarative description comprising a set of ground XML expressions and XML clauses. Its semantics is a set of ground XML expressions, which are explicitly described by the extensional database or implicitly derived from the intensional database and satisfy all the specified set of constraints.

Semantic query formulation and evaluation for XML databases

A semantic query attempts to help a user obtain or manipulate data in a database without knowing its detailed syntactic structure. Formulation and evaluation of semantic queries require schematic and other constraint information as well as general domain knowledge. A new approach to the formulation and evaluation of semantic queries for XML databases is proposed. It employs XML Declarative Description (XDD) - XML based knowledge representation - to model the databases together with the schemata of their XML elements and to represent domain knowledge resulting in a uniform representation of all the required information. Equivalent transformation (ET) - a new computation paradigm which transforms a representation into another while preserving their meanings - is used to optimize and evaluate the queries.

A Schema Language for MPEG-7

MPEG-7 provides a set of tools for the definition of a standard description for multimedia information. It uses XML Schema as its own Description Definition Language (DDL) to provide an ability to extend standard description to user application domains. However, due to its lack of expressive power, XML Schema cannot represent the implicit information of multimedia contents and hence cannot yield derived descriptions. In order to enhance the expressive power of multimedia annotations--described in terms of an XML document--and to maintain the advantages of XML Schema, there appears to be a need of a new schema language which can handle those abilities. XML Declarative Description (XDD) is a representation framework which can encode any XML document and application (e.g., XML Schema, RDF, RDF Schema, and DAML+OIL). It enhances XML expressive power by employing Declarative Description (DD) theory and also provides a mechanism for reasoning about new information from existing data. Moreover, it can specify constraints as well as ontological axioms. Thus, it is employed to construct a schema language for MPEG-7.