Null Queries with Interval-Valued Ambiguous Attributes.

We present a method for handling null queries that contains interval-valued ambiguous attributes. Null queries are queries that elicit a null answer from the database. Ambiguous attributes in null queries are attributes that are not defined in the original database schema but can be compounded from multiple rigid attributes in schema. Ambiguous attributes that are compounded from simple numbers were first studied by Nomura et al. (1992). In this work, we extend ambiguous attributes to fuzzy databases which contain data types of numbers and interval values. Fuzzy database management systems that can handle this type of ambiguous attributes not only can reduce the occurrences of null answers but also provide an improved query environment