Entity sorts: what are they? (English) Zbl 0633.03002

Materna, Pavel

Comput. Artif. Intell. 6, 321-324 (1987).

This is an explication of the terms “entity set” and “value set” as introduced by P. P. S. Chen [ACM Trans. Database Syst. 1, 9-36 (1976)] (“entity sort” and “descriptive sort” being used instead in the HIT data model [see J. Zlatuška: HIT data model. In: Proc. VLDB ’85, Stockholm (1985)]). It is shown that entity sorts can be represented (in databases) by means of descriptive sorts only, since an entity sort is always given through a property, i.e., through an intension, unlike descriptive sorts which are recursive classes.

MSC:

03A05	Philosophical and critical aspects of logic and foundations
03B65	Logic of natural languages
68P05	Data structures
68Q55	Semantics in the theory of computing

Keywords:

intension vs. extension; entity set; value set; databases; descriptive sorts; entity sort