Planning adequate audit strategies is a key success factor in "a posteriori" fraud detection, e.g., in the fiscal and insurance domains, where audits are intended to detect tax evasion and fraudulent claims. A case study is presented in this paper, which illustrates how techniques based on classification can be used to support the task of planning audit strategies. The proposed approach is sensible to some conflicting issues of audit planning, e.g., the trade-off between maximizing audit benefits vs. minimizing audit costs.

Planning adequate audit strategies is a key success factor in a posterion’ fraud detection, e.g., in the fiscal and insurance domains, where audits are intended to detect tax evasion and fraudulent claims. A case study is presented in this paper, which illustrates how techniques based on classification can be used to support the task of planning audit strategies. The proposed approach is sensible to some conflicting issues of audit planning, e.g., the trade-off between maximizing audit benefits vs. minimizing audit costs. A methodological scenario, common to a whole class of similar applications, is then abstracted away from the case study. The limitations of available systems to support the identified overall KDD process, bring us to point out the key aspects of a logic-based database language, integrated with mining mechanisms, which is used to provide a uniform, highly expressive environment for the various steps in the construction of the considered case-study.

This paper presents the main features of a Multimedia Query Language tailored for content-based similarity retrieval of multimedia objects. The Query Language processor is a component of a multimedia database system that adopts a model that permits both a structural representation of raw multimedia data and an automatically computed description of the multimedia data content. The Query Language is an extension of a traditional object-oriented query language. It allows to express restrictions on features, concepts and structural aspects of the multimedia database objects. In addition, the language supports the formulation of queries with imprecise conditions. The outcome of a query execution is an ordered set of pairs, each one consisting of an object and a measure of the similarity of the object with the criteria specified in the query.

Object-oriented database programming languages use a data model that, by its nature, leads to a hierarchical organisation of persistent data. The Multigranularity Locking (MGL) protocol is the concurrency control framework that allows to better analyse concurrent accesses to such hierarchy of data items. Furthermore, modern Object–Oriented Database Management Systems are organised accordingly to the client–server architecture, where the server component is often an object server. The application of software engineering criteria to the design of an object server usually leads to a system structured in interpretation layers. In a layered object server, the semantic knowledge necessary to decide which is the “best” granule to lock in the MGL data item hierarchy is distributed among all the system layers, therefore a suitable technique to co-ordinate such decisions is necessary. This paper presents some guidelines on the design of the hierarchical organisation of data items that should be used from an Object–Oriented Database Management System supporting the MGL protocol, and an original concurrency control technique called Expandable MGL that provides all the system layers with the ability of locking those granules that each layer considers more appropriate on the basis of its partial knowledge of a transaction’s behaviour.

Several research projects aim to integrate the functionalities of a database management system with those of a programming language. This is the main goal of Persistent Programming Languages. An open issue in these systems is to define and develop the important functionality that allows several endusers to concurrently access shared persistent data. This paper presents the problems we encountered and the techniques we used to provide the persistent programming language Galileo with the support for concurrent transactions that access a shared remote database. In our system, end—users can access a shared value environment and a shared type environment stored in a remote server. Every user can also use his own private persistent environments that are transparently integrated with the shared ones. Private environments are not directly visible to the other end-users, but there may be some subtle interactions on persistent private data due to inheritance. This system uses a strict two—phase locking technique to ensure serializability of concurrent transactions. Furthermore, it guarantees the recovery of persistent data in case of system and transaction failures.

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The authors describe an open system architecture for a persistent object store which is able to support a disparate range of persistent programming languages and their individual requirements. The ideal architecture would combine the flexibility and safety of a highly modular system with the performance of a tuned production system. The authors present an approach towards the ideal by realising part of the interface to the persistent object store in terms of conventions. This permits the costly use of interfaces to be circumvented on the basis of trust. The persistent object store may be used to construct programming language specific instances of the open architecture. To date the open architecture has been used to implement the persistent programming language Napier88, the functional programming language STAPLE, the object-oriented database programming language Galileo and the typeful programming language Quest