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A class of database schemes, called acychc, was recently introduced. It is shown that this class has a number of desirable properties. In particular, several desirable properties that have been studied by other researchers m very different terms are all shown to be eqmvalent to acydicity. In addition, several equivalent charactenzauons of the class m terms… (More)

This paper considers the efficient evaluation of recursive queries expressed using Horn Clauses. We define <italic>sideways information passing</italic> formally and show how a query evaluation algorithm may be defined in terms of sideways information passing and control. We then consider a class of information passing strategies which suffices to describe… (More)

A class of dependencies, tuple and equality generating dependencies, is defined, and the chase process is generalized to deal with these dependenetes. For total dependencies the chase is an exponential ttme decision procedure for the implication problem, and in some restricted cases it can be modified to run m polynomial Ume. For nontotal dependencies the… (More)

We investigate the inference rules that can be applied to functional and multivalued dependencies that exist in a database relation. Three types of rules are discussed. First, we list the well known rules for functional dependencies. Then we investigate the rules for multivalued dependencies. It is shown that for each rule for functional dependencies the… (More)

3 This article summarizes mathematical formalisms used to describe object and object-oriented databases. Different approaches were used to describe object databases, object database models respectively. We focus on algebraic approaches including graphs, monoid comprehensions, monads and semi-monads, and applied type theory. Especially we introduce formal… (More)

An Armstrong relation for a set of functional dependencies (FDs) is a relation that satisfies each FD implied by the set but no FD that is not implied by it. The structure and size (number of tuples) of Armstrong relatsons are investigated. Upper and lower bounds on the size of minimal-sized Armstrong relations are derived, and upper and lower bounds on the… (More)

Scoping, naming and binding are central concepts in the deenition and understanding of programming languages. With the introduction of sophisticated data models, these issues become important for query languages as well. Additionally, the goal of integrating query and programming languages requires a common basis for their operational semantics. We ooer… (More)

There is a class of database descriptions, involving one “acyclic” join dependency and a collection of functional dependencies, and nothing else, that appears powerful enough to describe most any real-world body of data in relational database terms. Further, this class has many desirable properties. Some properties make operations like updates… (More)

The problem of rewriting queries using views is to iind a query expression that uses only a set of views V and is equivalent to (or maximally contained in) a given query Q. Rewriting queries using views is important for query optimization and for applications such as information integration and data warehousing. Description logics are a family of logics… (More)

Various models and languages for describing and manipulating hierarchically structured data have been proposed. Algebraic, calculus-based and logic-programming oriented languages have all been considered. This paper presents a general model for complex values (i.e., values with hierarchical structures), and languages for it based on the three paradigms. The… (More)