Corporate databases increasingly are being viewed as potentially rich sources of new and valuable knowledge. Various approaches to"discovering" or "mining " such knowledge have been proposed. Here we identify an important and previously ignored discovery task, which we call data archaeology. Data archaeology is a skilled human task, in which the knowledge sought depends on the goals of the analyst, cannot be specified in advance, and emerges only through an iterative process of data segmentation and analysis. We describe a system that supports the data archaeologist with a natural, objectoriented representation of an application domain, a powerful query language and database translation routines, and an easy-to-use and flexible user interface that supports interactive exploration. A formal knowledge representation system provides the core technology that facilitates database integration, querying, and the reuse of queries and query results. Keywords: data archaeology, knowledge discov...

In a class hierarchy, a “role set ” is t,he set of classes where an object may reside simultaneously. A “migration pattern ” is a sequence of role sets. A “migration inventory, ” which is a set, of migrat,ion patterns, is viewed as a dynamic const,raintm on ohjrct migration. A set of transact ious is “sound ” wrt a11 inventory if it. generates only pat.t.t~rns in the invrntory; “complete ” if all pat,terns in the invent,ory can be generated. An initial stucly on characterizing migration inventories of transact,ions is presented. Three update languages are considered: SL which contains five operat,ors, CSL+ which ext rn(ls SL wit.h posit.ivc conditionals, and CSL which allows hot,h positive and negative condit.ionals. Four kinds of invent.orics are studied based on ln~znrss and znj~~,rtl~ntr s/art. It is shown that inventories produced by SL t,ransactions are regular and every regular inventory can be generated by SL transactions. Soundness and complet,eness for SL t,ransactions are decidahlt3. lnvc\llt,orics gpnrrated by CSL (CSL+) t,ra.nsactions arc r.e‘. and every r.e. inventory can be generat,rd by (:SL+ (CSL) transa.ctions under nonimmediate st,art,. It is also show t,hat, every r.e. immediate-start invent,ory can be obtained by a left quotient, of t,he invent,ory of CSL+ (CSL) transactions hy a regular seb. The exact, charact#erizat.ions are open. However, cvrry contrxl-frcr srt can be generat,ed. Soundness and rmllplPt~enms for ($1, (CSL+) t,ransa.ctions are undecidahlr. 1

The complexity and usefulness of large information systems are determined partly by their functionality, i.e., what they do, and partly by global constraints on their accuracy, security, cost, user-friendliness, performance, and the like. Even with the growing interest in developing higher-level models and design paradigms, current technology is inadequate both representationally for expressing such global constraints as formal non-functional requirements and methodologically for utilizing them in generating designs. We propose both a representational and methodological framework for non-functional requirements, focusing on accuracy requirements. With the premise that accuracy is an inherent semantic attribute of information, we take a first step towards establishing a representational basis for accuracy. To guide the design process and justify design decisions, we propose a goal-oriented methodology. In the methodology, accuracy requirements are treated as (potentially conflicting) go...

Abstract Achieving wide acceptance of formal methods in software development requires a smooth integration with requirements analysis, design and implementation. Especially for database application systems there exist well-known approaches to conceptual modeling as well as a sophisticated implementation technology on the basis of database programming languagues. The work described in this paper is based on a scenario, where the B method is coupled with a conceptual modeling language TDL and a database programming language DBPL. Both these languages can be represented in B. We concentrate on the problem of characterizing those B specifications that are sufficiently refined in order to be transformed into equivalent DBPL programs. This gives rise to some kind of implementability proof obligation. Moreover, we show that the transformation itself can be regarded as a term rewriting task based on a representation by term algebras of the languages involved. For this task we exploit order-sorted algebra by using the OBJ system.

Traditionally, substantial portion of database application semantics are captured through static and dynamic integrity constraints. The work reported in this paper exploits this fact by interpreting such database constraints as invariants and pre- and postconditions in the style of 'Z' [ScPi87, Spi88]. Database applications are specified by a conceptual modelling language close to TAXIS [MBW80], which has been enriched by constructs for a predicative speci cation style. Conceptual designs of database applications are formally analyzed for consistency and are refined, step by step, into efficient extended relational implementations. The reification of designs into implementations uses the formal framework of Abrial's Abstract Machines and generalized substitutions [Ab89]. It is shown that a small set of standard refinement rules is sufficient for a wide class of refinements. Furthermore, it is argued that the proposed proof-based approach has significant advantages over the traditional database technique...

Abstract Database application programs may be considered as good candidates for the application of formal specification methods, because much of the database and transaction semantics can be captured in terms of integrity constraints as well as pre- and postconditions. Furthermore, the use of current transaction models as units of database state transitions favours the use of Dijkstra's substitutions. Traditional DBMS solutions guarantee database integrity by expensive tests at transaction commit time. In the DAIDA project a different approach was taken interpreting database constraints as parts of formal specifications and by extracting correct database programs from such specifications. Database and transaction constraints are captured by an expressive semantic data model in the style of TAXIS, transformed into Abstract Machines and finally refined into AM versions that are equivalent to programs written in the strongly-typed database programming language DBPL. The work reported in this paper evaluates the DAIDA experience and addresses the shortcomings of DAIDA. A new formal specification language SAMT is proposed that essentially allows to structure and modularize specifications and to capture particular classes of constraints by its type system. Moreover, SAMT is considered as a framework for both the specification of database applications as well as the refinement of specifications into executable programs, thus eliminating some of the complexity issues found in the multi-language approach of DAIDA. 1 Introduction Formal specification and verification methods are gaining increasing interest in the area of database applications, where it is necessary to guarantee the consistency of long-lived, highly interrelated data. Unfortunately database applications were not yet the focal point of the formal specification community. The well-founded algebraic specifications [9, 19] follow more or less the line of abstract data types. The same applies for model-based specifications like VDM [3, 11], Z [17] and more recently the Abstract Machines [2].

We present first a series of examples involving the development of information systems, which suggest a number of desirable features for object-oriented specification techniques, especialy those supporting inheritance. Most of these features have difficulties with the so-called frame axioms --- assertions which state what values have been left unchanged by some procedure. We then examine the benefits and disadvantages of a variety of proposals for dealing with the frame problem, some of which are based on ideas presented earlier in the literature, while others are novel. The approaches are grouped into two families: one which introduces notational conventions/abbreviation for stating frame axioms, and one which embeds them into the language semantics. Of particular interest may be the introduction of a model-theoretic version of the assumption that things don't change unless they have to, and the possibility of relating this to syntactic techniques for stating such frame axioms in stan...