These methods are presented in the framework of a general query evaluation procedure
using the relational calculus representation of queries. In addition, nonstandard query …

Most existing statistical databases are mere collections of statistical files gathered for
specific purposes. Consequently, as they grow in size, users are faced with difficulties in …

In commercial network database management systems, set-valued fields and aggregate
functions are commonly supported. However, the relational database model, as defined by …

The relational model is now widely accepted as a model to represent various forms of data.
However, one of its limitations, namely the fact that it is restricted to first normal form (flat) …

We consider nested relations whose schemes are structured as trees, called scheme trees,
and introduce a normal form for such relations, called the nested normal form. Given a set of …

A methodology for adding the time dimension to the relational model is proposed and
relational algebra is extended for this purpose. We propose time-stamping attributes instead …

Various models and languages for describing and manipulating hierarchically structured
data have been proposed. Algebraic, calculus-based, and logic-programming oriented …

There is growing interest in abandoning the first-normal-form assumption on which the
relational database model is based. This interest has developed from a desire to extend the …

Search is a fundamental service in peer-to-peer (P2P) networks. However, despite
numerous research efforts, efficient algorithms for guaranteed location of shared content in …

This paper defines new constructs to support aggregation in the temporal query language
TQuel and presents their formal semantics in the tuple relational calculus. A formal …