this paper, including transaction logs and historical queries, the complexity of query evaluation, actualized transactions, logic programming approaches to updates, database views and state constraints. / This paper consolidates and expands on a variety of results, some of which have been described elsewhere (Reiter [46, 45, 44])

A family of extensions of SLDNF-resolution for normal abductive programs is presented. The main difference between our approach and existing procedures is the treatment of non-ground abductive goals. A completion semantics is given and the soundness and completeness of the procedures has been proven. The research presented here, provides a simple framework of abductive procedures, in which a number of parameters can be set, in order to fit the abduction procedure to the application under consideration.

We present SLDNFA, an extension of SLDNF-resolution for abductive reasoning on abductive logic programs. SLDNFA solves the floundering abduction problem: non-ground abductive atoms can be selected. SLDNFA provides also a partial solution for the floundering negation problem. Different abductive answers can be derived from an SLDNFA-refutation; these answers provide different compromises between generality and comprehensibility. Two extensions of SLDNFA are proposed which satisfy stronger completeness results. The soundness of SLDNFA and its extensions is proven. Their completeness for minimal solutions with respect to implication, cardinality and set inclusion is investigated. The formalisation of SLDNFA presented here is an update of an older version presented in [13] and does not rely on skolemisation of abductive atoms. 1

Negotiation between two agents is modelled as a one-time encounter between two extended logic programs. Each offers an answer set. Their mutual deal can be regarded as a trade on their answer sets. An agent can achieve this by weakening its program to surrender some literals that conflict with the offer of the other agent. We examine how ways of weakening affects the answer sets, and how they may be used to effect a deal. They are shown to satisfy the classificatios of outcomes that follow from known postulates for rational negotiation. 1

Abstract. When updating a knowledge base, several problems may arise. One of the most important problems is that of integrity constraints satisfaction. The classic approach to this problem has been to develop methods for checking whether a given update violates an integrity constraint. An alternative approach consists of trying to repair integrity constraints violations by performing additional updates that maintain knowledge base consistency. Another major problem in knowledge base updating is that of view updating; which determines how an update request should be translated into an update of the underlying base facts. We propose a new method for updating knowledge bases while maintaining their consistency. Our method can be used for both integrity constraints maintenance and view updating. It can also be combined with any integrity checking method for view updating and integrity checking. The kind of updates handled by our method are: updates of base facts, view updates, updates of deductive rules, and updates of integrity constraints. Our method is based on events and transition rules, which explicitly define the insertions and deletions induced by a knowledge base update. Using these rules, an extension of the SLDNF procedure allows us to obtain all possible minimal ways of updating a knowledge base without violating any integrity constraint. Key Words. View updating, integrity checking, integrity maintenance. 1.

We address the problem of formalizing the evolution of a database under the effect of an arbitrary sequence of update transactions. We do so by appealing to a first order representation language called the situation calculus, which is a standard approach in artificial intelligence to the formalization of planning problems. We formalize database transactions in exactly the same way as actions in the artificial intelligence planning domain. This leads to a database version of the frame problem in artificial intelligence. We provide a solution to the frame problem for a special, but substantial, class of update transactions. We next briefly describe some of the results obtained within this axiomatization. Specifically, we provide procedures for determining whether a given sequence of update transactions is legal, and for query evaluation in an updated database. These procedures have the nice property that they appeal to theorem-proving only with respect to the initial database state. We a...

. In the recent literature the issue of program change via updating rules (also known as revision rules) has been reduced to the issue of obtaining a new set of models, by means of the update rules, from each of the models of an initial program. Any program whose models are exactly the new set of models will count as an update of the original program. Following the classical approaches to theory updating, it is of course essential to start by specifying precisely how a program's models are to change, before even attempting to specify program change. But to stop there is to go only halfway. Another limitation of existing approaches to logic program updating concerns their not dealing with 3-valuedness, i.e. with partial models. The limitation is twofold: on the one hand, only programs under 2-valued semantics are approachable; on the other, when there are contradictory update rules, in lieu of leaving undefined the effects of the contradictory rules and keeping those of the others, no u...

This paper is devoted to the problem of view updates in deductive databases. In this context, derived or intensional predicates correspond to the views of traditional relational databases. The view update problem is thus the problem of accomplishing the update of an intensional predicate by modifying appropriately the underlying relations in the extensional part of the database. In the case

We propose a new method for view updating in deductive databases. The method is based on events and transition rules, which explicitly define the insertions and deletions induced by a database update. Using these rules, an extension of the SLDNF procedure allows us to obtain all valid translations of view update requests. The main advantages of the method are its simplicity, the uniform treatment of insert and delete requests and the integration of integrity checking during the derivation process. The method has the full power of the methods developed so far, without some of their limitations. 1. Introduction The view update problem of relational and deductive databases has attracted a lot of research during the past years [1,2,5,6,7,8,9,11,13,16]. The aim is to provide effective methods for translating view updates into (correct) database updates. Two basic approaches have been proposed to solve the problem. The first suggests treating views as abstract data types, so that the defin...

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...