A Logic Approach for MPEG-7 XML Document Queries.
Peiya Liu, Amit Chakraborty, Liang H. Hsu · 2001
Many query languages are currently being proposed for specifying XML document retrievals. The expressive power and usefulness of these query languages is really based on their embedded formalisms and intended XML document applications. The emerging MPEG-7 multimedia standard uses XML Schema:Datatypes for multimedia content descriptions and has posed an interesting challenge to XML query language design for XML document retrievals. Most XML query language proposals have limitations in specifying queries for this type of XML documents. In this paper, we have identified some critical specification issues in MPEG-7 XML queries and propose an XML query language, MMDOC-QL with multimedia query constructs. MMDOC-QL is based on a logic formalism, called path predicate calculus. In this path predicate calculus, the atomic logic formulas are element predicates rather than relation predicates in relational calculus. In this path calculus query language, queries in this calculus are equivalent to finding all proofs to existential closure of logical assertions in the form of path predicates that the tree document elements must satisfy. Spatial, temporal and visual datatypes and relationships can also be described in this formalism for content retrieval.