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In the process of rule generation from databases, the volume of generated rules often greatly exceeds the size of the underlying database. Typically only a small fraction of that large volume of rules is of any interest to the user. We believe that the main challenge facing database mining is what to do with the rules after having generated them. Rule post-processing involves selecting rules which are relevant or interesting, building applications which use the rules and finally, combining rules together to form a larger and more meaningful statements. In this paper we propose an application programming interface which enables faster development of applications which rely on rules. We also provide a rule query language which allows both selective rule generation as well as retrieval of selected categories of rules from the pre-generated rule collections. [ABSTRACT FROM AUTHOR]

For the last many years, workflow management (WFM) has been the focus of intense activity in terms of products, standards and research work worldwide. WFM integrates concepts from many areas of computer science. Numerous workflow companies, and industrial and academic research groups are in existence now. Several conferences and workshops relating to WFM are being held regularly. The popularity of the worldwide web, extranets and electronic commerce is further increasing the desirability of standards in the workflow arena to enable interoperability. The recent emphasis on supply chain reengineering as a means of reducing costs and improving responsiveness is also a factor in this regard. In this extended abstract, which is a condensed version of a paper which appears in the proceedings of the NATO Advanced Study Institute in Workflow Management and Interoperability held in Istanbul in August 1997, I briefly summarize the recent trends in WFM products, standards and research. I address technical as well as business trends. [ABSTRACT FROM AUTHOR]

In this paper, we consider conjunctive queries with built-in predicates of the form X < Y, X ≤ Y, X = Y, or X ⊋ Y, where X and Y are variables or constants from a totally ordered domain. We present a sufficient and necessary condition to test containment among these kinds of queries. Klug [8] left the problem open for the case when the domain is nondense, like the integers. Ullman [11] gave only a sufficient condition for the containment of conjunctive queries with built-in predicates and integer variables. Our test is based in a method that uses a new idea: the representation of an infinite number of databases by a finite set of, what we call, canonical databases, that use variables that denote uninterpreted constants. [ABSTRACT FROM AUTHOR]

In multidatabase systems the heterogeneity and the autonomy of the sites preclude the applicability of the classical query optimization algorithms used in distributed database systems, and therefore new approaches have to be investigated. In this paper we propose a distributed optimization algorithm that makes very general assumptions on the cost function, and on the degree of autonomy of the federated sites. The algorithm is based on a cooperative approach where cost of a query execution plan is evaluated as the composition of the cost estimates produced by the local sites where each part of the computation has to be performed. During the optimization process larger and larger partial execution plans are considered, and the the relative cost estimates are exchanged between the sites. Duplicated and unnecessary computation is avoided by discarding as soon as possible partial plans that are dominated by an equivalent one. The paper substantially extends the results of a previous paper, where we first introduced the idea of cooperative optimization, by removing major restrictions on the query model, and by considering not only sequential execution plans but also parallel ones. [ABSTRACT FROM AUTHOR]

In the paper a particular approach to transaction management in databases supporting collaborative applications is proposed. It is based on a new transaction model which allows practically unrestricted collaboration among members of the same team. The basic assumption of this model is that collaborating users try to solve their access conflicts on a higher level than the level of a database management system. Users are not mutually isolated, as it happens in classical databases. They can freely negotiate, presenting their intentions concerning future work. The proposed approach was verified in Agora prototype which is a Web-based conferencing system, offering conference participants a flexible tool for collaborative document writing. Agora is implemented on the top of Oracle RDBMS. [ABSTRACT FROM AUTHOR]

Workflow management systems aim at controlling the execution of complex application processes in distributed environments. Workflow management currently moves from modeling and executing mostly static structured workflows to supporting flexible workflows, which are typically executed in distributed and heterogeneous environments. This paper discusses the use of distributed object technology to built a flexible workflow management system. In particular, based on a detailed object-oriented object model, we discuss the dynamic behavior of workflow instances, and we show how flexibility requirements have influenced our design. [ABSTRACT FROM AUTHOR]

Transaction dependencies have been recognized as a valuable method in describing restrictions on the executions of sets of transactions. A transaction closure is a generalized transaction structure consisting of a set of related transactions which are connected by special dependencies. Traditionally, relationships between transactions are formulated by binary dependencies. However, there are applications scenarios where dependencies must be specified among more than two transactions. Since n-ary dependencies cannot be expressed by binary dependencies, appropriate extensions are required. In this paper, we extend the concept of transaction closure by ternary termination dependencies. We show how n-ary termination dependencies can be expressed by binary and ternary termination dependencies. As a result, we present rules for reasoning about the combination of these termination dependencies. [ABSTRACT FROM AUTHOR]

Search agents in the World-Wide Web are able to find documents which match user-submitted queries. As the number of matching documents returned by the agent is often very large, it would be easier for the user to browse through clusters rather than individual documents when searching for the documents which really satisfy his information needs. In this paper we introduce a new approach to term weighting for the document similarity measures needed in clustering. The approach is based on term occurrence frequencies within the set of documents which match an initial query. We suggest that this approach might perhaps be useful in noise reduction in the very rich and heterogenous environment of the Web. [ABSTRACT FROM AUTHOR]

In this paper, we propose an approach and a general schema of algorithms for automatic detection of conflicts between schema and underlying object base. Our approach is distinguishable by first discovering schema from given set of objects and then comparing it to the existing schema for discovery of schema conflicts. The approach is based on the comparison of the two inheritance lattices: one constructed on the basis of class library and another discovered from object base using one of the general conceptual classification methods. [ABSTRACT FROM AUTHOR]

In the paper we survey research results of the Database Research Group at Charles University Prague during last 10 years. Its activities have been focused mainly on applying a functional approach to conceptual modelling and modelling of objects via relational databases. The former research direction influenced also an approach to a formalization of object-oriented models and, recently, OLAP and data warehouses modelling. The latter research concerned a persistence of objects and a study, how to implant high-level query capabilities in C++. In the context of the ADOORE project, a practical implementation — a general library (GENLIB) is now at disposal, where objects are stored in a relational database. To enhance queering objects, high-level query capabilities are possible. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of propagating local structural schema changes to an already acquired integrated schema of a federation. Our approach is to regard this problem from a schema integration point of view. The main contribution is the development of a framework for performing evolution of an integrated schema without information loss and avoiding as much as possible re-integration steps. [ABSTRACT FROM AUTHOR]

Data processing in modern information systems often require access to data stored in multiple heterogeneous databases. Schema integration is an important step for providing database integration and interoperability of distributed database systems. The process of schema integration requires knowledge of the semantics of component database schemas and must be supported by a database designer. The paper presents various models containing data versions and time components used in business systems and their possible semantic heterogeneity. Also, the techniques for integration of schemas containing version models are discussed and the methodology for creating an integrated schema with versions is proposed. [ABSTRACT FROM AUTHOR]

Schema comparison is essential for integrating different database schemata. Since the semantics of a schema is also represented by its integrity constraints, they must be considered by a correct schema comparison method. Especially the extensional relationships between classes are determined by the relationship between the corresponding integrity constraint sets. In this paper, we work out the relationships between different types of integrity constraints. As a result, we present rule for comparing integrity constraint sets. These rules can be used after a schema conforming step, where naming, type and structural conflicts are solved, to exactly fix the extensional relationship between object classes. [ABSTRACT FROM AUTHOR]

This paper describes an interface for querying databases integrating versions (DBiV). This interface gives a representation of the database schema as a graph of nodes and links and defines a graphic language for both querying versions and objects living together in the database. Expressing a query consists in selecting links and performing operations from nodes of the graph. The graphically performed operations are algebraic functions. This interface is intended for casual users. [ABSTRACT FROM AUTHOR]

In this paper we study data replication in a mirrored disk system. Free disk space is exploited by keeping replicas of specific cylinders at appropriate disk locations. Assuming an organ-pipe arrangement we calculate the expected seek distance by varying the probability cylinder access under different distributions. Also, analytic formulae are derived for the expected seek distance under replication and comparison with the conventional (without replication) mirrored disk system is performed. [ABSTRACT FROM AUTHOR]

An implementation of persistent object store for real-time systems with strict processing time constraints is a challenging task, because many traditional database techniques, e.g. transaction management schemes, are not applicable for such systems. This paper examines technical and business requirements for one particular class of such systems and describes an architecture based on distributed shared virtual memory. The major contributions are: use of distributed dynamic hashing to achieve load balancing and tight coupling of transaction and virtual memory management, which allows local scheduling of read-only transactions. [ABSTRACT FROM AUTHOR]

The rapid growth in data volume, user base, and data diversity render Internet-accessible information increasingly difficult to be used effectively. In this paper we discuss the issues involved with knowledge discovery in knowledge bases, in particular the WWW, by presenting a general architecture and describing how it has been instantiated in a functional system we developed. The system attempts to concurrently maximize and optimize the resource/knowledge discovery, and custimize the information to individual users. A number of machine learning techniques have been employed in the development of the system for comparative reasons — results are presented and discussed. [ABSTRACT FROM AUTHOR]

Knowledge discovery in databases (KDD) and data mining represent very important tools for processing and analysing data in large databases. The combination of powerful KDD and data mining techniques and sophisticated resources of object-oriented database systems brings even more considerable results. These emerging tools and techniques require a powerful data mining query language serving as an interface between applications and data mining tools. This motivates us to design an object-oriented data mining query language for mining different kinds of knowledge from object-oriented databases. We introduce an overview of this language, its syntax and semantics in this paper and some examples of practical use will be shown too. [ABSTRACT FROM AUTHOR]

Mining association rules is an important data mining problem. Association rules are usually mined repeatedly in different parts of a database. Current algorithms for mining association rules work in two steps. First, the most frequently occurring sets of items are discovered, then the sets are used to generate the association rules. The first step usually requires repeated passes over the analyzed database and determines the overall performance. In this paper, we present a new method that addresses the issue of discovering the most frequently occurring sets of items. Our method consists in materializing precomputed sets of items discovered in logical database partitions. We show that the materialized sets can be repeatedly used to efficiently generate the most frequently occurring sets of items. Using this approach, required association rules can be mined with only one scan of the database. Our experiments show that the proposed method significantly outperforms the well-known algorithms. [ABSTRACT FROM AUTHOR]

In this paper we discuss first experiences and results of current work on the BioBench, an integrated information system for Bioinformatics. Since the major part of Bioinformatic data is distributed in many heterogeneous systems all over the world one has to deal with problems of integration of heterogeneous systems. Especially semi-structured data, presented via WWW-interfaces has to be integrated. Therefore, we focus on the aspects of acquisition, integration and management of the data for the BioBench. First we give a short motivation of the project and an overview of the system. In the main follows a discussion of schema derivation for the WWW-interfaces. Thereby, we discuss the application of domain knowledge and automatic grammar generation. Finally we briefly describe an automatic wrapper generation approach, supporting high quality wrappers as well as wrapper modification according to local schema or format evolutions. [ABSTRACT FROM AUTHOR]

With the advent of object-oriented database systems there is a need to migrate/integrate old systems, mainly relational ones, to/into object-oriented systems. In this paper we propose a method to automatically translate SQL queries to OQL ones. The method is based on a graph representation of SQL queries. This graph is enriched and transformed in a series of stages which take into account the caracteristics of the object schema with respect to the relational one (new entity type, ISA relationship, class hierarchy, etc.). This semantic enrichment allows an optimized translation of the SQL queries compared with a purely syntaxic translation. [ABSTRACT FROM AUTHOR]

This paper presents a flexible database schema transformational framework. Flexibility is achieved by adopting a generic model for describing database schemas and a transformational language able to represent all the correctness preserving schema transformations. This framework, originally defined for schema design, is also applicable for supporting other activities related to the database life-cycle. As an illustrative example, this paper shows how it can be used to support a database reverse engineering process. [ABSTRACT FROM AUTHOR]

This paper contains a description of the optimisation method for large databases with heterogeneous applications. This method makes it possible to automatically define the physical structure of a relational database. The input to the optimisation algorithm are the SQL queries stored in text files which are executed on the database server in a real life applications. Our tool recognises the classes of SQL queries and their frequency, analyses semantics and as a result prepares suggestions for the following parameters of physical definition of the database: the key and physical structure of a table (from amongst Btree, Isam, Hash and Heap), set of optimal indexes (this means their key as well as physical structure). The principal information which the system uses within the database optimisation process are: frequency and classes of SQL queries in an application and the data value distributions. The selection of the optimal configuration of the database relies a Electre Method which is a multicriteria optimal choice method. The use of these techniques increases the efficiency of the system first of all because it reduces the number of pages which are read and written to disks as a result of the optimal choice of the physical structures of tables and indexes. The system supports Oracle, Informix, Sybase and CA-Ingres. [ABSTRACT FROM AUTHOR]

The general aim of the KOSTRA project, initiated by Statistics Norway, is to set up a data reporting chain from the norwegian municipalities to a central database at Statistics Norway. In this paper, we present an innovative data model for supporting a data analysis process consisting of two sequential data production phases using two conceptional database schemes. A first data schema must provide a sound basis for an efficient analysis reflecting a multidimensional view on data. Another schema must cover all structural information, which is essential for supporting the generation of electronic forms as well as for performing consistency checks of the gathered in-formation. The resulting modeling approach provides a seamless solution for both proposed challenges. Based on the relational model, both schemes are powerful to cover the heterogeneity of the data source, handle complex structural information, and to provide a versioning mechanism for long term analysis. [ABSTRACT FROM AUTHOR]

Message oriented middleware (MOM) services, based on the concept of persistent queues, are widely used for reliable asynchronous communication to deal with the disadvantages of the closely coupled communication model. This paper introduces some new functionality for queuing services (QS) in order to make them more powerful for the need of modern application programs and presents JPMQ, a sample implementation of these concepts. As such, JPMQ provides an object-oriented type system for messages, dynamic selection and ordering of messages as well as content-based priorities. Moreover, JPMQ offers transactional concepts in order to cope with concurrent access and failure recovery. [ABSTRACT FROM AUTHOR]

In this paper we address aspects of traceability in Information Systems design, particularly with those methodologies utilizing rich, and possibly multiple (behavioural) models. We consider this issue within the broader context of IS development, and focus on the potential for communication among human actors. Specifically, we consider the question of repository design for supporting design activities. We illustrate this through a Web-based visualization tool for Extended Entity-Relationship (EER) modeling represented in a repository based on the Case Data Interchange Format (CDIF). Such a tool offers a degree of independence with respect to CASE tools used within an organization, and validation methods chosen by an organization. [ABSTRACT FROM AUTHOR]

A commonly followed approach in database design is to collect user views on the database and to develop the conceptual schema of the database by integrating these views. The design of object-oriented databases involves the design of object behavior next to the design of object structure. Object-oriented design notations usually represent object behavior at two levels of detail: by activities (which correspond to methods at the implementation level) and by object life-cycles which model the dynamics of objects over their lifetime. This paper discusses the integration of views of object life-cycles that are represented by behavior diagrams, which model the behavior of objects by activities and states corresponding to transitions and places of Petri nets. The presented approach is particularly relevant for the design of business processes, a major application domain of object-oriented database systems. [ABSTRACT FROM AUTHOR]

Mining for association rules between items in a large database of sales transactions is an important database mining problem. However, the algorithms previously reported in the literature apply only to static databases. That is, when more transactions are added, the mining process must start all over again, without taking advantage of the previous execution and results of the mining algorithm. In this paper we present an efficient algorithm for mining association rules within the context of a dynamic database, (i.e., a database where transactions can be added). It is an extension of our Partition algorithm which was shown to reduce the I/O overhead significantly as well as to lower the CPU overhead for most cases when compared with the performance of one of the best existing association mining algorithms. [ABSTRACT FROM AUTHOR]

Multimedia databases include many types of new data. One common property of these data items is that they are very large. We exploit the concept of transformational representations to logically store images without the bitmap. This technique is similax to views in traditional database systems. The technique is useful when users axe editing images in the database to create new images. Our method produces significant space savings over already compressed images, and potentially greater savings for video and audio. The method requires the support of multimedia editors. This paper emphasizes the meta-structure needed by the database to support multimedia editing. [ABSTRACT FROM AUTHOR]

In this paper the establishment of a supporting knowledge base for a looselycoupled federation of heterogeneous databases available over a computer network is described. In such a federation, user information requirements are not static. The changes and evolution in user information needs reflect both the changing information available in the federation as databases join and leave it and their contents change, and the varied requirements the users have of the information available in the federation. As a user's awareness of the contents of the federation improves, their requirements from it often evolve. This means that users need different integrating views if they are to realise its full potential. The knowledge base will be used to help users of the federated databases to create views of the federation and to determine the available information in the federation. The knowledge base (KB) is created and evolved incrementally by analysing both meta-data of databases as they join the federation and views as they arc created over the databases in the federation. The KB is organised as a semantic network of concept clusters, and can be viewed as a conceptual model describing the semantics of all databases in the federation. It records not only concepts and their inter-relationships defined in schemas but also their frequency of occurrence within the federation, and is used both as a semantic dictionary and as a basis to enrich schemas Romantically during the detection of semantic relationships among schema components when creating user views. We semantically enrich schemas prior to integration by generating the best subnetwork that spans the concepts common to the schema and the knowledge base and then by unifying this sub-network with the schema. Hence the terms in schemas arc given interpretations not by considering them in isolation but by taking into account contexts, derived from the knowledge base with respect to those schema terms. An architecture to facilitate the establishment of this knowledge base and to exploit its functionality is described. The novelty of our research is that we create a knowledge base for a federation by gathering and organising information from it to assist groups of users to create dynamic and flexible views over the databases in the federation which meet their dynamic information requirements. This knowledge base enables reuse of the semantics when creating views. [ABSTRACT FROM AUTHOR]

Correct transformations and integrations of schemata within the process of federated database design have to encompass existing local integrity constraints. Most of the proposed methods for schema transformation and integration do not sufficiently consider explicit integrity constraints. In this paper we present an approach to deal with integrity constraints. Our approach bases on the idea to relate integrity constraints to extensions. A set of elementary operations for schema restructuring and integration is identified. For these operations we define major rules for dealing with integrity constraints. By means of a small example we then demonstrate the application of these rules. [ABSTRACT FROM AUTHOR]

Deductive database languages have often evolved with little regard for ongoing developments in other parts of the database community. This tendency has also been prevalent in deductive object-oriented database (DOOD) research, where it is often difficult to relate proposals to the emerging standards for object-oriented or object-relational databases. This paper seeks to buck the trend by indicating how deductive languages can be integrated into the ODMG standard, and makes a proposal for a deductive component in the ODMG context. The deductive component, which is called DOQL, is designed to conform to the main principles of ODMG compliant languages, providing a powerful complementary mechanism for querying, view definition and application development in ODMG databases. [ABSTRACT FROM AUTHOR]

Current database management system technology is unable to provide adequate support for Nomadic Computing. Mobile applications require systems which are sufficiently lightweight and customisable to provide high performance while consuming minimal power, yet extensible enough to adapt to a constantly changing environment. Current DBMS architectures do not provide this level of customization or adaptability. In this paper we introduce Component-Based Database Management Systems (CBDMS) and discuss their suitability for mobile computing. [ABSTRACT FROM AUTHOR]

Active object-oriented database systems are a commonly accepted solution for capturing the time- and context-dependent knowledge of non-standard applications. Several attempts have been made already to integrate active concepts into object-oriented database systems and to increase the expressive power of event specification languages. However, this has often been done without considering the consequences for the implementation. The present paper tries to fill this gap. The main focus is on describing design and implementation issues concerning composite event management within the active object-oriented database system TriGS. Thereby, we concentrate on the idiosyncratic features of TriGS, which are composite events spanning several transactions and even several applications, smooth integration of composite event detection with rule scheduling, and the inheritance of rules. [ABSTRACT FROM AUTHOR]

This paper proposes an approach to building event services for active database applications. It introduces dimensions to characterize distributed event definition, detection, production and notification. The core of our approach is a parametric event service called QUETZAL that has three interfaces, each of them implementing the given dimensions as parameters. Therefore, different event (detection) models may be defined simply by giving values to these parameters. Such an approach provides flexible definition, detection, production and notification of events according to application needs. Since our service is based on a consumer-producer principle, it can be combined with any producer and consumer, facilitating in this way communication and collaboration between distributed components such as classical applications, database transactions, primitive event detectors or event notification tools. [ABSTRACT FROM AUTHOR]

Current needs of industry required the development of advanced database models like mobile databases, active databases, and fuzzy databases. Fuzzy concepts are adapted to the field of databases in order to deal with ambiguous, uncertain data. Fuzziness comes into picture in mobile databases especially with moving objects. Incorporating fuzziness into rules would improve the effectiveness of active databases. Rules can be utilized in mobile databases to form a more powerful system, namely an active mobile database. In this paper we investigate the ways in which the concepts developed for fuzzy systems can be integrated to active mobile databases. [ABSTRACT FROM AUTHOR]

To avoid OID index retrieval becoming a bottleneck, efficient buffering strategies are needed to minimize the number of disk accesses. In this paper, we develop analytical cost models which we use to find optimal sizes of the index page buffer and the index entry cache, for different memory sizes, index sizes, and access patterns. Because existing buffer hit estimation models are not applicable for index page buffering in the case of tree based indexes, we have also developed an analytical model for index page buffer performance. The cost gain from using the results in this paper is typically in the order of 200-300%. Thus, the results should be of valuable use in optimizers and tools for configuration and tuning of object-oriented database systems. [ABSTRACT FROM AUTHOR]

DO2 is a deductive object-oriented database developed at the National University of Singapore. The system aims to integrate deductive and object-oriented paradigms and use their advantages to overcome both the paradigms' respective weaknesses. DO2 differs from conventional deductive object-oriented databases in its' key-based approach for OIDs, pro-active approach to resolving inheritance conflicts and natural interpretation of negation using the not predicates. This paper describes the structure, language, and implementation of DO2. [ABSTRACT FROM AUTHOR]

This paper studies the problem of selecting rules to fire in real-time active databases in order to avoid missing action deadlines. We give an algorithm that executes at every fixed time interval (called the Rule Selection Period), and satisfies three properties, namely, the Completion Property, the Duration Property, and the Priority Property. We develop a probabilistic model, and an inexpensive (polynomial-time) algorithm for the satisfaction of the Completion Property. We show that the problem of satisfying the Duration and the Priority Properties at the same time is NP-Complete. We then give two heuristic-based algorithms, and briefly summarize the associated experimental results. [ABSTRACT FROM AUTHOR]

The main argument of the paper is that database understanding (or reverse engineering) requires sophisticated program understanding techniques, and conversely. Database reverse engineering (DBRE) can be carried out following a generic methodology, one of the phases of which consists in eliciting all the implicit and untranslated data structures and constraints. Evidences of these hidden constructs can be found by analysing how the programs use and update the data. Hence the need for program analysis techniques such as searching for clichés, dependency analysis, program slicing and synthetic views. The paper explains how these techniques contribute to DBRE, and describes DB-MAIN, a programmable and extensible CASE environment that supports DBRE through program understanding techniques. [ABSTRACT FROM AUTHOR]

Many organizations nowadays own several information systems which represent a mine of possible information resources whose effective exploitation is becoming a key issue in many application contexts. A major problem to be faced within such contexts is the semantic normalization of scheme objects used in heterogeneous, independent and pre-existing databases as to single out differences and similitudes among data whereby a consistent, integrated view of available information can be obtained. To solve large instances of this problem, the development of automatic support tools appears to be mandatory. This paper gives a contribution in this framework by presenting algorithms for extracting useful properties holding among objects belonging to sets of pre-existing database schemes. The algorithms are capable of deriving both nominal and structural properties of scheme objects starting from database scheme descriptions. [ABSTRACT FROM AUTHOR]

Extending the usability of merged database and text-retrieval systems by building on an object-oriented database management system (OODBMS) can offer better and complementary advantages to both database and information retrieval systems (IRS). In this paper, we present a new approach for integrating OODBMSs and IRSs that maintains the flexibility and avoids overheads of mapping process, by means of wrapping the documents and encapsulating signature based IR methods into storable objects which are being stored in the database. In particular, we demonstrate how to apply such an integration approach to a special problem domain: a multi-lingual information retrieval system. In our framework, a sound platform and query facilities offered by the underlying object-oriented database can further enhance the original IR functions and be applicable to the construction of multimedia-document based digital libraries. [ABSTRACT FROM AUTHOR]

Signature file acts as a filter to eliminate the unqualified data items for an information request. The contribution of this paper is two-fold. First, we propose a methodology for structured database. The main idea of decomposition amounts to dividing the relations of database into subrelations called 'rectangle'. Owing to the reduction of storage overhead, rectangular decomposition has a direct benefit in a reduction of false drop probability. Second, we extend the use of rectangular decomposition to partitionning signature file called Super-Rectangular Organisation SRO. The choice of the criteria to cluster signatures is based upon the relationship between the associated objects. Our main concern is to study the performance of this method in terms of this ability to reduce the search space and false drop probability. We also perform simulation experiments by comparing several methods like S-tree and Quick filter. The results show that the SRO improves performance significantly in term of retrieval time and false drop probability. [ABSTRACT FROM AUTHOR]

The focus of this paper is information brokers within Information Discovery (ID). We describe Cumulative Duality matrices, an instrument to deal with design criteria for such information brokers. ID is the synthesis of Information Retrieval and Information Filtering, where information brokers act as middle-agents. There are numerous design criteria for information brokers. Since these stem from ID, they exhibit a dual nature. The duality of the criteria is shown to be cumulative. In the form of a matrix, cumulative duality can be used as a design instrument for information brokers. [ABSTRACT FROM AUTHOR]

This paper describes an agent based architecture to manage workflows. The agents, rather than predefined rules, determine the flow of work, enabling them to cater for unexpected inputs. The agents in this distributed system use organisational rules, as well as the state of the decision making environment to control the flow of work. An experimental agent-based workflow system based on the World Wide Web to manage the processing of applications received by a university department from potential research students is described. [ABSTRACT FROM AUTHOR]

In the paper a particular approach to transaction management in databases supporting collaborative applications is proposed. It is based on a new transaction model which allows practically unrestricted collaboration among members of the same team. The basic assumption of this model is that collaborating users try to solve their access conflicts on a higher level than the level of a database management system. Users are not mutually isolated, as it happens in classical databases. They can freely negotiate, presenting their intentions concerning future work. [ABSTRACT FROM AUTHOR]

This paper focuses on the database modeling of spatiotemporal phenomena. Their components and behavior are analyzed and a formal framework with a small set of concepts-namely objects, attributes, relationships, fields, and constraints, with spatial and temporal dimension-for their definition is provided. A mathematical model for the expression of spatiotemporal constraints, based on the aforementioned concepts, is presented. Next, all the described concepts are translated into modeling constructs-namely entities, attributes, relationships, fields, phenomena and constraints-to enrich the Entity-Relationship (ER) model for the conceptual design of spatiotemporal applications dealing with phenomena. We give the semantics and syntax of the prototypical extended ER; any other model augmented by the same constructs can be used for this purpose. An example demonstrates the applicability, modeling power and ease-of-use of this proposal. [ABSTRACT FROM AUTHOR]

In this paper we describe an approach to rule base V&V founded on a N-dimensional tesseral representation of space. The advantages offered by the representation are that it is simple, concise and lends itself to computationally effective manipulation of objects (defined in the representation) using standard integer addition and subtraction. The encapsulation of a rulebase in this tesseral representation — as a multi-dimensional "arena" — then provides an appropriate mechanism for the application of spatial algorithms to address rulebase verification. The algorithms make full use of the advantages associated with the representation, and consequently offer a significant reduction in time complexity over more traditional approaches to rulebase verification. In particular this paper demonstrates the potential of tesserally encoded rulebases the full impact of which, in the author's opinion, has yet to be explored. [ABSTRACT FROM AUTHOR]

In this paper, we propose a temporal link mechanism for 'time-dependent' hypermedia. It has become a serious problem to maintain link information at all times according to updating. It is very important to keep consistency and maintain the updates, especially for broadcast hypermedia, which are transmitted from a server to a client via the internet or a broadcasting system. The mechanism we propose supports links in broadcast hypermedia to designate adequate anchors automatically. We also describe the implementation issues of the link mechanism. [ABSTRACT FROM AUTHOR]

Prototype databases are needed in any information system development process to support data-intensive applications development. It is common practice to populate these databases using synthetic data. This data usually bears little relation to the application's domain and considers only a very reduced subset of the integrity constraints the database will hold during operation. This paper claims that in situations where operational data is available, as is the case in information system evolution and migration, a sample of this data must be used to create a prototype database. The paper outlines a method for consistently sampling a database. This method uses a new concept, the Insertions Chain Graph, to assist in selecting instances so that the resulting Sample Database reaches a consistent state, a significant task of database sampling. [ABSTRACT FROM AUTHOR]