Issue No. 05 - October (1994 vol. 6)
DOI Bookmark: http://doi.ieeecomputersociety.org/10.1109/69.317704
<p>This paper proposes the use of a type abstraction hierarchy as a framework for deriving cooperative query answers. The type abstraction hierarchy integrates the abstraction view with the subsumption (is-a) and composition (part-of) views of a type hierarchy. Such a framework provides multilevel object representation, which is an important aspect of cooperative query answering. The concept of pattern that specifies one or more conditions on an object is also proposed. Patterns have smaller granularity than types, and thus provide more specific semantic information. Cooperative query answering consists of query relaxation, generalization, specialization, and association on patterns. Query relaxation can be explicitly specified by the user or implicitly performed by the system. The implicit and explicit relaxations can also be combined and performed interactively by both the system and the user. CSQL, an extension of SQL for cooperative query answering, is also proposed. Preliminary experimental results reveal that the proposed type abstraction hierarchy provides an organized structure representing concepts at different knowledge levels in various domains, and provides a systematic and efficient method for cooperative query answering.</p>
deductive databases; database theory; query processing; SQL; query languages; relational databases; knowledge representation; cooperative query answering; type abstraction hierarchy; cooperative query answers; subsumption; composition; type hierarchy; multilevel object representation; granularity; semantic information; query relaxation; generalization; specialization; association; CSQL; SQL; type abstraction; knowledge representation; query language; query rewrite; deductive database
W. Chu and Q. Chen, "A Structured Approach for Cooperative Query Answering," in IEEE Transactions on Knowledge & Data Engineering, vol. 6, no. , pp. 738-749, 1994.