A graph-oriented object database model (GOOD) is introduced as a theoretical basis for database systems in which manipulation as well as conceptual representation of data is transparently graph-based. In the GOOD model, the scheme as well as the instance of an object database is represented by a graph, and the data manipulation is expressed by graph transformations. These graph transformations are described using five basic operations and a method construct, all with a natural semantics. The basic operations add and delete objects and edges in function of the matchings of a pattern. The expressiveness of the model in terms of object-oriented modeling and data manipulation power is investigated. Index terms: Database models, query languages, graph transformations, objectoriented databases, user interfaces. Preliminary versions of this paper were presented at the 9th ACM Symposium on Principles of Database Systems [16] and the 1990 ACM SIGMOD International Conference on Management of D...

) Marc Gyssens y University of Limburg Laks V.S. Lakshmanan z Concordia University Iyer N. Subramanian z Concordia University Abstract Tables are one of the most natural representations of real-life data. Previous table-based data models (such as relational, nested relational, and complex objects models) capture only a limited variety of real-life tables. In this paper, we study the foundations of tabular representations of data. We propose the tabular database model for handling a broad class of natural data representations and develop tabular algebra as a language for querying and restructuring tabular data. We show that the tabular algebra is complete for a very general class of transformations and show that several languages designed for very different purposes can naturally be embedded into the tabular model. We also demonstrate the applicability of our model as a theoretical foundation for on-line analytical processing (OLAP), an emerging technology for complementing the r...

The expressive power of the family wILOG (:) of relational query languages is investigated. The languages are rule based, withvalue invention and stratified negation. The semantics for value invention is based on Skolem functor terms. Westudy a hierarchy of languages based on thenumber of strata allowed in programs. We first show that, in presence of value invention, the class of stratified programs madeoftwo stratahas the whole expressive power of the family, thus expressing the computable queries. Wethen show that the language wILOG 6= of programs with non-+ y and without negation expresses the monotone queries, and that the language wILOG 1 2 #: of semipositive programs expresses the semimonotone queries.

Databases provide one of the main concrete scenarios for finitemodel theory within computer science. This paper presents an informal overview of database theory aimed at finite-model theorists, emphasizing the specificity of the database area. It is argued that the area of databases is a rich source of questions and vitality for finite-model theory.

The goal of the paper is to develop a graphical formalism for specifying queries and views within the sketch data model (SkeDM) introduced in [17]. Sketches are directed multigraphs in which some diagrams are labeled with special markers. These markers denote predicates and operations over diagrams of sets and functions. Given a signature of operations (query language), any sketch (database schema) can be extended with derived items denoting data that can be retrieved from the database. Views to a schema S are then sketch morphisms v : SV ! S 0 from some sketch (view schema) SV into an augmentation of S with derived items, S 0 . In this way one obtains a unifying graph-based formal language for data and metadata definition and manipulation. In particular, a formalized specification framework for heterogeneous multibase systems can be built. The approach is described with a number of examples and then precisely formalized. The main technical contribution is the development of alge...

A graphical model for describing schemes and instances of object-databases and a graphical data manipulation language based on pattern matching, called PaMaL, are introduced. The operations of PaMaL (addition and deletion of nodes and edges) use patterns to indicate the parts of the instance that are affected by the operation. We give the syntax and semantics of the operations and the programming constructs (loop, procedure and program) of PaMaL. We add a reduce-operation to work with a special group of instances, the reduced instances. 1 Introduction One of the first visual or graphical interfaces for databases was QBE [Zlo77]. It introduced a new way of user-database interaction, by providing the user some tools to interact directly with the database and its structure. Since then, the research of visual interfaces has evolved in two directions. One group develops specialized interfaces for geographical or pictorial information (some relevant information can be found in [vl, Coo93])...

The paper presents a survey of the main formal rule-based languages and semantics. Both procedural (fixpoint) and declarative (model-theoretic) semantics are defined and discussed, including inflationary and noninflationary fixpoint semantics, and the semipositive, stratified and well-founded semantics. The relative expressive power and complexity of the various languages are provided. Nondeterministic rule-based languages are also discussed, and it is shown how nondeterminism can circumvent some difficulties concerning the expressive power of the deterministic languages. Finally, languages with value invention (in the spirit of object-creation in oodbs) are presented and issues of expressive power specific to such languages are discussed.

A graph-based model for describing schemes and instances of object databases together with a graphical data manipulation language based on pattern matching are introduced. The data model allows the explicit modeling of classes and relations which contain objects and associations, respectively.

The generic graph machine, a Turing machine-like computation model for generic graph functions, is introduced. A configuration of this machine consists of a number of machine instances that each are in a state and point to two nodes of a graph. During the execution of a step, the machine instances perform in parallel a local transformation on the graph and are each replaced by a number of other machine instances. It is proved that the generic graph machines express a large and natural class of generic graph functions. 1 Introduction If we represent a database as a (labeled) graph, database manipulations can be modeled as partial functions mapping graphs to graphs [3]. We call such functions graph functions. However, not all graph functions can be interpreted as data manipulations. Indeed, they should satisfy at least the following two requirements. First, the function should be computable in the classical sense, i.e., there must be a Turing machine which, when presented an encoding o...

. Recently, Abiteboul and Kanellakis introduced the notion of determinate query to describe database queries having the ability to create new domain elements. As there are no natural determinate-complete query languages known, more restrictive (the constructive queries) and more general (the semi-deterministic queries) notions of query were considered. Here, we show that the advantage of the second approach over the first is not so much in increased expressiveness, but in the ability of expressing queries more efficiently. 1 Introduction Over a decade ago, Chandra and Harel [7] proposed a language-independent notion of completeness with respect to domain-preserving database queries: a query language is complete if it can express all Turing-computable partial functions from databases to databases that are invariant under every permutation of the universe of possible domain values. The latter criterion, nowadays known as genericity (e.g., [4]), ensures that queries can be comput...