Lattice-Structured Domains, Imperfect Data and Inductive Queries

The relational model, as proposed by Codd, contained the concept of relations as tables composed of tuples of single valued attributes taken from a domain. In most of the early literature this domain was assumed to consist of elementary items such as simple (atomic) values, de ned complex data types or arbitrary length binary objects. Subsequent to that the nested relational or non- rst normal form model allowing set-valued or relation-valued attributes was proposed. Within this model an attribute could take multiple values or complete relations as values. This paper presents a further extension to the relational model which allows domains to be de ned as a hierarchy (speci cally a lattice) of concepts, shows how di erent types of imperfect knowledge can be represented in attributes de ned over such domains, and demonstrates how lattices allow the accommodation of some forms of inductive queries. While our model is applied to at relations, many of the results given are applicable also ...

• Type: Conference
• Year: 2000
• Where: DEXA
• Authors: Sally Rice, John F. Roddick
• Keywords: Database, DEXA 2000, Ned Complex Data, Relational Model, Single Valued Attributes