Integrity constraints are very useful in many contexts, such as, for example, deductive databases, abductive and inductive logic programming. However, fully testing the integrity constraints after each update or modification can be very expensive and methods have been developed which simplify the integrity constraints. In this paper, we pursue the goal of writing this simplification procedure as a meta-program in logic programming and then using partial deduction to obtain pre-compiled integrity checks for certain update patterns. We argue that the ground representation has to be used to write this metaprogram declaratively. We however also show that, contrary to what one might expect, current partial deduction techniques are then unable to specialise this meta-interpreter in an interesting way and no pre-compilation of integrity checks can be obtained. In fact, we show that partial deduction (alone) is not able to perform any (sophisticated) specialisation at the object-level for meta...

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Abstract. Complete checks of database integrity constraints may be prohibitively time consuming, and several methods have been suggested for producing simplified checks for each update. The present approach introduces a set of transformation operators that apply to database integrity constraints with each operator representing a concise, semanticspreserving operation. These operators are applied in a procedure producing simplified constraints for parametric transaction patterns, which then can be instantiated and checked for consistency at run-time but before any transaction is executed. The operators provide a flexibility for other database enhancements and the work may also be seen as more systematic and general when compared with other approaches. The framework is formulated with first-order clause logic but with the perspective of being applied with present-day database technology. 1

Abstract. Both aggregates and arithmetic built-ins are widely used in current database query languages: Aggregates are second-order constructs such as COUNT and SUM of SQL; arithmetic built-ins include relational and other mathematical operators that apply to numbers, such as ≤ and +. These features are also of interest in the context of database integrity constraints: correct and efficient integrity checking is crucial, as, without any guarantee of data consistency, the answers to queries cannot be trusted. In this paper we propose a method of practical relevance that can be used to derive, at database design time, simplified versions of such integrity constraints that can be tested before the execution of any update. In this way, virtually no time is spent for optimization or rollbacks at run time. Both set and bag semantics are considered. 1

We discuss the extended LP environment of the project VEGA (knowledge validation and exploration by global analysis), a toolbox that supports the development and maintenance of declarative knowledge bases. The knowledge is represented in a declarative language that merges Horn logic with finite domains, sort hierarchies, functions, and integrity constraints. These KBs may contain problemsolving knowledge, ontologies, and cases. The VEGA environment includes tools that take into account these different kinds of knowledge to ensure the integrity of the knowledge base during its entire life-time. Besides such knowledge-validation components, VEGA provides for the interactive exploration of knowledge by inductive components, e.g. a generator of rules from facts. VEGA also allows to link foreign tools, and is thus an open architecture. The tools can be synergetically configured by visual programming. Knowledge validation can for example be performed on the output of knowledge exploration. ...

It is shown that constraint logic is useful for evaluation of integrity constraints in deductive databases. Integrity constraints are represented as calls to a metainterpreter for negation-as-failure implemented as a constraint solver. This procedure, called lazy negationas -failure, yields an incremental evaluation: It starts checking the existing database and each time an update request occurs, simplified constraints are produced for checking the particular update and new constraints corresponding to specialized integrity constraints are generated for the updated database. 1 Introduction There is a relationship between integrity constraints in databases and the constraints of constraint logic programming going beyond the partial overlap of the names applied for these phenomena. Both concern conditions that should be ensured for systems of interdependent entities: the different tuples in a database, and the set of variables in a program execution state. Both relate to problems that e...

Abstract. In concurrent database systems, correctness of update transactions refers to the equivalent effects of the execution schedule and some serial schedule over the same set of transactions. Integrity constraints add further semantic requirements to the correctness of the database states reached upon the execution of update transactions. Several methods for efficient integrity checking and enforcing exist. We show in this paper how to apply one such method to automatically extend update transactions with locks and simplified consistency tests on the locked entities. All schedules produced in this way are conflict serializable and preserve consistency. For certain classes of databases we also guarantee that the amount of locked database entities is minimal. 1

Abstract. Database integrity constraints, understood as logical conditions that must hold for any database state, are not fully supported by current database technology. It is typically up to the database designer and application programmer to enforce integrity via triggers or tests at the application level, which are difficult to maintain and error prone. Two important aspects must be taken care of. 1. It is too time consuming to check integrity constraints from scratch after each update, so simplified checks before each update should be used relying on the assumption that the current state is consistent. 2. In concurrent database systems, besides the traditional correctness criterion, the execution schedule must ensure that the different transactions can overlap in time without destroying the consistency requirements tested by other, concurrent transactions. We show in this paper how to apply a method for incremental integrity checking to automatically extend update transactions with locks and simplified consistency tests on the locked elements. All schedules produced in this way are conflict serializable and preserve consistency in an optimized way. 1

We define sustained models and show that they coincide with partial stable models. On the basis of sustained models, we define a semantics of integrity in deductive databases. The semantics of integrity is innovative, in the sense that it is threevalued and not prevalent wrt either satisfaction or violation of integrity. As opposed to that, conventional semantics are prevalent, and do not consider open states that neither satisfy nor violate integrity. As a refinement of the three-valued semantics, a non-prevalent two-valued semantics of integrity is specified at last. Introduction Interpretations are usually represented by subsets of the Herbrand base of the underlying language. Intuitively, each atom in an interpretation is assigned the value true, and each atom in the complement is assigned false. Interpretations which model the intended meaning of a database are fairly easy to obtain in case there is no negation in the body of clauses (cf. [vK] [Ll]). However, the intended meanin...