Patrizia Asirelli

Integrity constraints in logic databases

Abstract We consider logic databases as logic programs and suggest how to deal with the problem of integrity constraint checking. Two methods for integrity constraint handling are presented. The first one is based on a metalevel consistency proof and is particularly suitable for an existing database which has to be checked for some integrity constraints. The second method is based on a transformation of the logic program which represents the database into a logic program which satisfies the given integrity constraints. This method is specially suggested for databases that have to be built specifying, separately, which are the deductive rules and the facts and which are the integrity constraints on a specific relation. Different tools providing for the two mechanisms are proposed for a flexible logic database management system.

Language Extensions for Semantic Integration of Deductive Databases

A language in support of semantic integration of deductive databases is proposed. The language allows one to construct mediators by extending logic programming with a suite of operators for composing programs and message passing features. The abstract semantics and implementation techniques of the extensions are discussed, and an example of integration of databases supporting libraries and departments is used to illustrate the usefulness of the approach.

Using MedLan to integrate geographical data

Abstract In this paper we focus on the application of the declarative mediator language MedLan to the integration of geographical information systems and deductive databases. The language provides the ability to handle multiple logic theories via the notion of program expressions. We present an application example that deals with finding the best habitat for wild boars in a region of Tuscany.

Applying restriction constraints to deductive databases

An operation for restricting deductive databases represented as logic programs is introduced. The constraints are coded in a separate database, and the operator puts the two databases together in order to provide a restricted view of the original database. The operator is given a semantics in terms of the immediate consequence operator. Then a transformational implementation is given and its correctness is proved with respect to the abstract semantics. The approach is presented at first for positive programs and it is then extended to take negation as failure into account.

Graphics by a Logic Database Management System

Abstract The GEDBLOG system allows applications which manipulate graphic objects to be developed following a declarative definitional style. GEDBLOG supports the consistent design and prototyping of graphic applications through an incremental development and makes it possible to guarantee automatically that the application meets its specifications. Typical GEDBLOG applications have graphics as their characterizing element and can be found, for example, in the CAD/CAM, visual languages or graphical interface areas. The system is obtained by integrating a graphical data language in an existing logic database management system, EDBLOG, so that graphic and non-graphic information is handled in a uniform declarative way.

Enhancing configuration facilities in software development: a logic approach

The paper focuses on the suitability and advantages of a Logic Data Base approach to manage configurational aspects within Programming Environments. It describes part of a work which proposes Logic Data Bases as effective tools to be integrated with existing programming environments to increase their formalization and automation capabilities. In order to present the idea and its implications, we discuss, as a practical example, the integration of a prototype Logic DBMS (EDBLOG) with a Unix-like environment for configuration management. In that framework, a possible realization of the Make facility is shown. The advantages of the proposed approach are mainly concerned with the easiness of extention of the programming environment and of the configuration environment to deal with concepts which, in general, are very expensive to provide,e.g. histories and versions management.

An Operator for Composing Deductive Databases with Theories of Constraints

An operation for restricting deductive databases represented as logic programs is introduced. The restrictions are represented in a separate deductive database. The operation is given an abstract semantics in terms of the immediate consequence operator. A transformational implementation is given and its correctness is proved with respect to the abstract semantics.

Selective Refutation of Integrity Constraints in Deductive Databases

In this paper we have presented a method that allows the selection of those branches of a derivation tree that contain a specific clause as input clause. We have applied such method to integrity constraint checking but it seems useful in other application areas as well.

Using Logic Databases in Software Development Environments

The paper discusses a role that logic programming can play in programming development environments. In particular, the suitability of logic databases to handle a specific programming development activity, notably configuration, is presented according to the experience gained while using a prototype logic database to support Ada-like configuration facilities [Asirelli 87a] and a Unix-like make facility [AsirelIi 87b]. The work reported in the paper is part of a more general project whose aim is to propose logic data bases as effective tools to be used as project databases. To this respect it is useful to point out that the relations induced on modules by the configuration activity are typical examples of relations that must be dealt with by a project database.

The Constraint Operator of MedLan: Its Efficient Implementation and Use

A declarative mediator language, based upon operations among logic theories is introduced. In particular we concentrate on the constraint operator. The denotational semantics of the language is introduced together with the definition of a bottom-up efficient implementation. The use of the constraint operator for security within a mediator architecture for database integration is suggested and presented by means of a simple example.