Coherent Integration of Databases by Abductive Logic Programming

Abstract

We introduce an abductive method for a coherent integration of independent data-sources. The idea is to compute a list of data-facts that should be inserted to the amalgamated database or retracted from it in order to restore its consistency. This method is implemented by an abductive solver, called Asystem, that applies SLDNFA-resolution on a meta-theory that relates different, possibly contradicting, input databases. We also give a pure model-theoretic analysis of the possible ways to `recover' consistent data from an inconsistent database in terms of those models of the database that exhibit as minimal inconsistent information as reasonably possible. This allows us to characterize the `recovered databases' in terms of the `preferred' (i.e., most consistent) models of the theory. The outcome is an abductive-based application that is sound and complete with respect to a corresponding model-based, preferential semantics, and -- to the best of our knowledge -- is more expressive (thus more general) than any other implementation of coherent integration of databases

Distance-Based Repairs of Databases

“…By this, only erroneous fragments of tuples are modified. 3 The condition that in every tuple at least one component belongs to HU(DB) is meant to exclude degenerated cases, in which a tuple consists of null values only. A potential repair R of DB is an update of D that preserves IC with respect to S (R |= S IC).…”

“…In the context of database systems, this notion was introduced by [1], and then considered by many others, including [2-4, 6, 7, 13, 22, 21, 29, 34]. Some implementations of these methods are reported in [3,18,19,28]. Despite their syntactic and semantic differences, as well as the different notions of repair used by different consistency maintenance formalisms, the rationality behind all these methods is of keeping the 'recovered' data 'as close as possible' to the original (inconsistent) data.…”

An ID-Logic Formalization of the Composition of Autonomous Databases

“…-Systems for data integration, in which the major concern is to resolve contradictions that may occur when the distributed data is amalgamated (see, e.g., [1][2][3][4][5]8]). …”

“…relate the different terminologies of the local databases and that of the global integrity constraints, 2. identify inconsistencies (i.e., violations of integrity constraints) and resolve them by making some (minimal amount of) changes in the unified database, 3. search for solutions that may lie outside the active domain of the databases (in order, e.g., to satisfy the second constraint above).…”

“…In this paper we present a composition system that generalizes the schema integration process introduced in [30] and at the same time enhances the abductive system for data integration introduced in [3], by using the same logical formalism. The outcome is a uniform solution for database composition, which to the best of our knowledge is more comprehensive (with respect to the expressive power of the underlying language, the amount of integration methods that are supported, and the mediation capabilities mentioned in Example 1) than any other approach implemented by similar systems.…”