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The research presented in this paper is situated in the framework of constraint databases that was introduced by Kanellakis, Kuper, and Revesz in their seminal paper of 1990. In this area, databases and query languages are defined using read polynomial constraints. As a consequence of a classical result by Tarski, first-order queries in the constraint database model are effectively computable, and...
This paper presents a first prototype of a constraint database for spatial information, dedale. Implemented on top of the O2 DBMS, data is stored in an object-oriented framework, with spatial data represented using linear constraints over a dense domain. The query language is the standard OQL, with special functions for constraint solving and geometric operations. A simple geographical application...
We consider spatial databases that can be defined in terms of polynomial inequalities, and we are interested in monotonic transformations of spatial databases. We investigate a hierarchy of monotonicity classes of spatial transformations that is determined by the number of degrees of freedom of the transformations. The result of a monotonic transformation with kdegrees of freedom on a spatial...
Temporally constrained matching in a persistent and declarative object-oriented system is introduced as a semantic alternative to the existing approaches to the covariance/contravariance problem. While the existing object-oriented type systems are based on subtyping, F-bounded polymorphism and matching, this language system is based entirely on inheritance, which is identified with matching. The type...
Existential quantification of procedures is introduced as a mechanism for languages with dynamic typing. It allows abstraction over types whose representations require to be manipulated at run time. Universal quantification, the mechanism normally associated with procedural type abstraction, is shown to be unsuitable for this style of abstraction. For many such procedures only a single type specialisation...
This paper develops a database query language called Transducer Datalog motivated by the needs of a new and emerging class of database applications. In these applications, such as text databases and genome databases, the storage and manipulation of long character sequences is a crucial feature. The issues involved in managing this kind of data are not addressed by traditional database systems, either...
Several researchers have considered integrating multiple unstructured, semi-structured, and structured data sources by modeling all sources as edge labeled graphs. Data in this model is self-describing and dynamically typed, and captures both schema and data information. The labels are arbitrary atomic values, such as strings, integers, reals, etc., and the integrated data graph is stored in a unique...
In this paper VQL, a language devoted to querying data stored in multiversion databases, is proposed. A multiversion database represents several states of the modeled universe. A formal model of such a database is presented. VQL, which is based on a first order calculus, provides users with the ability of navigating through object versions, and through the states of the universe modeled by the multiversion...
We present a formal data model for views in Object DataBase Systems (ODBS) as a transformation mechanism for databases. Our model relaxes the usual coustraiul, where an object belongs to a single class while using a generalization of referent and eatables a deterministic creation of derived objects with complex object identifiers. We define an IQL-like language which enables the manipulation of such...
Previous research on materialized views has primarily been in the context of flat relational databases—materialized views defined in terms of one or more flat relations. This paper discusses a broader class of view definitions-materialized views defined over a nested data model such as the nested relational model or an object-oriented data model. An attribute of a tuple deriving the view can be a...
We examine the power of incremental evaluation systems that use an SQL-like language for maintaining recursively-defined views. We show that recursive queries such as transitive closure, and “alternating paths” can be incrementally maintained in a nested relational language, when some auxiliary relations are allowed. In the presence of aggregate functions, even more queries can be maintained, for...
It is a folk result that relational algebra or calculus extended with aggregate functions cannot compute the transitive closure. However, proving folk results is sometimes a nontrivial task. In this paper, we tell the story of the work on expressive power of relational languages with aggregate functions. We also prove by far the most powerful result that describes the expressiveness of such languages...
Recently there was some attention on integration of description logics of the AL-family with rule-based languages for querying relational databases such as Datalog, so as to achieve the best characteristics of both kinds of formalisms in a common framework. Formal analysis on such hybrid languages has been limited to computational complexity: i.e., how much time/space it is needed to answer to a specific...
This paper investigates the optimisation of aggregation functions in the context of computationally complete database programming languages and aims to generalise and provide a unifying formal foundation for previous work. We define a ‘fold’ operator φ over collection types in terms of which operations such as selection, projection, join and group-by can be defined, as well as aggregation functions...
Multidimensional databases are large collections of data, often historical, used for sophisticated analysis oriented to decision making. This activity is supported by an emerging category of software technology, called On-Line Analytical Processing (OLAP). In spite of a lot of commercial tools already available, a fundamental study for OLAP systems is still lacking. In this paper we introduce a model...
This paper introduces the specification language CoCaA. The features of COCGA are designed for the specification of both organisational and transactional aspects of cooperative activities, based on the CoACT cooperative transaction model. The novelty of the language lies in its ability to deal with a broad spectrum of cooperative applications, ranging from cooperative document authoring to workflow...
In this paper we introduce Business Conversations as a highlevel software structuring concept for distributed systems where multiple autonomous agents (possibly in different organizational units) have to coordinate their long-term activities towards the fulfillment of a cooperative task. We first motivate Business Conversations as a system model suitable for the description of human-human, human-software...
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