A formal basis for an abbreviated concept-based query language

Concept-based query languages allow users to specify queries directly again st conceptual schemas. The primary goal of their development is ease-of-use and user-friendliness. However, existing concept-based query languages req uire the end-user to explicitly specify query paths in totality, thereby re ndering such systems not as easy to use and user-friendly as they could be. The conceptual query language (CQL) discussed in this paper also allows en d-users to specify queries directly against the conceptual schemas of datab ase applications, using concepts and constructs that are native to and exis t on the schemas. Unlike other existing concept-based query languages, howe ver, CQL queries are abbreviated, i.e., the entire path of a query does not have to be specified. CQL is, therefore, an abbreviated concept-based quer y language. CQL is developed with the aim of combining the ease-of-use and user-friendliness of concept-based languages with the power of formal langu ages. It does not require end-users to be familiar with the structure and o rganization of the application database, but only with the content. Therefo re, it makes minimal demands on end-users' cognitive knowledge of database technology without sacrificing expressive power. In this paper, the formal semantics and the theoretical basis of CQL are presented. It is shown that, while CQL is easy to use and user-friendly, it is nonetheless more than fi rst-order complete. A contribution of this study is the use of the semantic roles played by entities in their associations with other entities to supp ort abbreviated conceptual queries. Although only mentioned here in passing , a prototype of CQL has been implemented as a front-end to a relational da tabase manager. (C) 2001 Published by Elsevier Science B.V. All rights rese rved.