This paper presents a language of update programs that integrates logical queries, bulk updates and hypothetical reasoning in a seamless manner. There is no syntactic or semantic distinction between queries and updates. Update programs extend logic programs with negation in both syntax and semantics. Users can specify bulk updates in which an arbitrary update is applied simultaneously for all answers of an arbitrary query. Hypothetical reasoning is naturally supported by testing the success or failure of an update. We describe an alternating fixpoint semantics of update programs and show that it can express all nondeterministic database transformations. Current techniques of logical query evaluation can be generalized for effective execution of updates. Keywords: bulk updates, hypothetical reasoning, logical queries, alternating fixpoint semantics, database languages. 1 Introduction Updates play an important role in modeling dynamic behaviors in database systems [1, 24]. Various lang...

This paper proposes a new approach to model deductive object databases. Each object database is described by means of a Datalog language extended with extensional updates, called U-Datalog. Objects can change state and cooperate. We introduce an extension of U-Datalog to approach the problem of composition among object databases. It can be used for modular database design and for cooperation among deductive objects. The resulting language has a clear semantics for the evolution of objects and for modeling the transactional behavior of the resulting database. Finally, we describe some architectural issues of the prototype which has been developed.

In this paper, we show how techniques from disjunctive logic programming and classical first-order theorem proving can be used for efficient (deductive) database updates. The key idea is to tranform the given database together with the update request into a disjunctive logic program and apply disjunctive techniques (such as minimal model reasoning) to solve the original update problem. We present two variants of our algorithm both of which are of polynomial space complexity. One variant, which is based on offline preprocessing, is of polynomial time complexity. We also show that both variants are rational in the sense that they satisfy certain rationality postulates stemming from philosophical works on belief dynamics.

This position paper provides a general description of the field of active databases, focusing on the main problems yet to be solved; suggests that deductive databases may contribute to understand some of these problems; and indicates classes of applications that can be specified in a declarative way. Premise The field of active databases has recently emerged as one of the most important directions of evolution of database technology. Significant progress has been achieved both in the research environment and in the commercial world; these are reflected on one side by the relative1 large number of recent articles on the subject (see [12]), and on the other side by the increas-ing number of research prototypes and commercial systems which provide active behavior (see [ 13,16,19]). In general, this behavior is supported through inte-grated, low-level production rule facilities allowing for the automatic execution of data manipulation opera-tions when certain events occur and/or certain condi-tions are met. In spite of the rapid development of this field, sev-eral problems remain to be solved in order for active databases to become widespread and fully accepted. A first problem concerns the understanding of the semantics of a collection of production rules. This amounts to underst anding precisely under which con-ditions rules are executed and the effect of their execu-tion. Difficulties are mostly due to the variety of pro-duction rules which have been proposed; differences are due to: 0 The event upon which a rule is triggered:- A database modification (through insert, delete, or update operations).- A retrieval operation.- A time-related event. 0 The rule consideration time with respect to transactions. Rules can be executed in the context of the transactions that update the database, or be executed asynchronously. In the former case, rule consideration can be:- After each update operation.- At user-defined rule execution points.

An extension of predicate logic, called Transaction Logic, is proposed, which accounts in a clean and declarative fashion for the phenomenon of state changes in logic programs and databases. Transaction Logic has a natural model theory and a sound and complete proof theory, but unlike many other logics, it allows users to program transactions. This is possible because, like classical logic, Transaction Logic has a "Horn" version which has a procedural as well as a declarative semantics. In addition, the semantics leads naturally to features whose amalgamation in a single logic has proved elusive in the past. These features include both hypothetical and committed updates, dynamic constraints on transaction execution, nondeterminism, and bulk updates. Finally, Transaction Logic holds promise as a logical model of hitherto non-logical phenomena, including so-called procedural knowledge in AI, active databases, and the behavior of object-oriented databases, especially methods with side ef...

this paper, we show how techniques from first-order theorem proving can be used for

One of the most difficult problems on the way to an integration of Object-Oriented and Logic Programming is the modeling of changeable object state (i.e. object dynamics) in a particular logic in order not to forfeit the declarative nature of LP. Classical logic is largely unsuitable for such a task, because it adopts a general (both temporally and spatially), Platonic notion of validity, whereas object state changes over time and is local to an object. This paper presents the problem and surveys the state-of-the-art approaches to its solution, as well as some emerging, promising new approaches. The paper tries to relate the different approaches, to evaluate their merits and deficiencies and to identify promising directions for development. Keywords: Object-Oriented Logic Programming, mutable object state, survey. 1 The Problem: Dynamics of Objects From the research literature on integration of Object-Oriented Programming (OOP) and Logic Programming (LP) one gets the impression that ...

In this paper we propose two interpretations of the event rules [Oli91] which provide a common framework for classifying and specifying deductive database updating problems such as view updating, materialized view maintenance, integrity constraints checking, integrity constraints maintenance, repairing inconsistent databases, integrity constraints satisfiability or condition monitoring. Moreover, these interpretations allow us to identify and to specify some problems that have received little attention up to now like enforcing or preventing condition activation. By considering only a unique set of rules for specifying all these problems, we want to show that it is possible to provide general methods able to deal with all these problems as a whole. 1 Introduction Deductive databases generalize relational databases by including not only base facts and integrity constraints, but also deductive rules. Using these rules, derived facts may be derived from facts explicitly stored. Among oth...

. Updates are a crucial component of any database programming language. Even the simplest database transactions, such as withdrawal from a bank account, require updates. Unfortunately, updates are not accounted for by the classical Horn semantics of logic programs and deductive databases, which limits their usefulness in real-world applications. As a short-term practical solution, logic programming languages have resorted to handling updates using ad hoc operators without a logical semantics. A great many works have been dedicated to developing logical theories in which the state of the underlying database can evolve with time. Many of these theories were developed with specific applications in mind, such as reasoning about actions, database transactions, program verification, etc. As a result, the different approaches have different strengths and weaknesses. In this survey, we review a number of these works, discuss their application domains, and highlight their strong and weak points...

Two different approaches have been traditionally considered for dealing with the process of integrity constraints enforcement: integrity checking and integrity maintenance. However, while previous research in the first approach has mainly addressed efficiency issues, research in the second approach has been mainly concentrated in being able to generate all possible repairs that falsify an integrity constraint violation. In this paper we address efficiency issues during the process of integrity maintenance. In this sense, we propose a technique which improves efficiency of existing methods by defining the order in which maintenance of integrity constraints should be performed. Moreover, we use also this technique for being able to handle in an integrated way the integrity constraints enforcement approaches mentioned above. 1. Introduction Database updating has attracted a lot of research during last years [Abi88]. Several problems may arise when updating a deductive database [TU95]. O...