Ulrich Schiel

Towards multi-level and modular conceptual schema specifications

The specification of the conceptual schema for a data base application is divided into levels. It is argued that, at the highest level, a direct description of the characteristics of the information kept in a data base and of the constraints governing their existence and transformation of its components characterizes what a particular data base is in a more fundamental way (hence at a higher and more stable level) than the operations that happen to be used for data base manipulation. At a next lower level a specification based on operations, using the encapsulation strategy of abstract data types, is introduced, followed by a specification based on representations used in semantic data models. The discussion includes constraints involving temporal aspects. Modularization is also discussed as another dimension in the specification process, orthogonal to the division into levels.

Visual query operators for temporal databases

Many recent proposals in the literature present easy-to-use query languages, based on visual representations of the database and direct manipulation mechanisms. Such proposals essentially deal with conventional query operations, whereas little effort is devoted to investigate friendly environments for querying temporal databases. Nevertheless, temporal aspects are generally considered extremely relevant in several database applications. Thus, the various users should be provided with powerful and simple query systems also exhibiting temporal features. While attempting to meet this need, we propose a visual query system for temporal databases. It adopts a diagrammatic representation of the database schema (including temporal classes and relationships), on which conventional as well as temporal visual query operators can be applied. In this paper we concentrate on the temporal operators, showing both examples of usage and formalization.

Abstractions in semantic networks: axiom schemata for generalization, aggregation and grouping

A successful complex expert system, Kardios model of the human heart is designed for the diagnosis of cardiac arrhythmias. Kardio is highly skilled in the reading of ECG recordings, and can be used as a diagnostic tool in ECG interpretation. In this groundbreaking account, the authors show how the model was compiled, by means of qualitative simulation and machine learning tools, into various representations that are suited for particular expert tasks. They investigate a hierarchical organization of a qualitative model and outline an experiment whereby the construction of a deep model is automated by machine learning techniques. The book contains a complete model of the electrical system of the heart.

Querying spatio-temporal databases using a visual environment

Visual Query Systems (VQS) are becoming a very attractive field of research, especially for advanced database systems such as spatial and temporal ones. However, most of the visual query proposals support either spatial or temporal data but not both. This paper presents a new VQS which supports querying spatio-temporal data. The main idea is to provide a web-based, user-friendly, and visual environment for querying generic spatio-temporal databases. Therefore end users do not need to worry about neither data schemas nor query language syntax. The proposed VQS is based on well-established standards such as SQL and OpenGIS, and it is flexible to be used in many database systems with support for spatial data.

Formalizing visual interaction with historical databases

Recent database applications are typically oriented towards a large set of non-expert users, and therefore, they need to be equipped with suitable interfaces facilitating the interaction with the system. Moreover, the incorporation of the time dimension in database systems is a desirable feature. Indeed, several temporal data models and the corresponding textual query languages have been proposed. However, there is a limited amount of research concerning the investigation of user-oriented languages for querying temporal databases. Our proposal addresses such a need. In particular, we propose a visual query environment, namely Temporal Visual Query Environment (TVQE) which provides an easier interaction of the user with temporal databases. The system adopts a diagrammatic representation of the database schema (including temporal classes and relationships) and a graphical notebook as interaction metaphor. In our approach, non-database experts are released from syntactical difficulties which are typical of textual languages, and they can easily express temporal queries by means of elementary graphical operations (e.g. click on a node label). Differently from many proposals in the field of visual query languages, the language underlying TVQE is provided with formal syntax and semantics. It is based on a minimal set of temporal graphical primitives (TGPs), which are defined on a Temporal Graph Model (TGM), with visual syntax and object-based semantics. In this paper we mainly concentrate on the formal aspects of TVQE, and provide some hints on the visual interaction mechanisms and implementation issues.

SIM-a system for semi-automatic indexing of multilingual documents

With the growing significance of digital libraries and the Internet, more and more electronic texts become accessible to a wide and geographically disperse public. This requires adequate tools to facilitate indexing, storage, and retrieval of documents written in different languages. We present a method for semi-automatic indexing of electronic documents and construction of a multilingual thesaurus, which can be used for query formulation and information retrieval. We use special dictionaries and user interaction in order to solve ambiguities and find adequate canonical terms in the language and an adequate abstract language-independent term. The abstract thesaurus is updated incrementally by new indexed documents and is used to search documents concerning terms in a query to the document base.

A Internet e seu impacto nos processo de recuperação da informação

We show how information technology, specially the Internet, is promoting a globalization in information resources and retrieval. The different available interactions with the Internet are presented and the most important bibliographic research services are introduced.

The problem of identification

The existing models for database applications use a few fundamental concepts for the description of the world to be modeled. The most common of these concepts is the <italic>entity</italic>, also called object, element, concept, information, token, data or value. Entities are identifiable and distinguishable existing things of the real world. In general the concept of entity, is used only for static things whose existence does not depend directly from other entities, in contrast to the dynamic happenings called <italic>events</italic> and the existence of some dependency between two or more entities called <italic>relationship</italic> (or attribute or property) which can exist only in conjunction with the related entities. More complex combinations of entities, relationships and events we call <italic>facts</italic>. Therefore “<italic>John has broken his leg yesterday and is in Santa Clara Hospital</italic>” is a fact which combines the event of “<italic>breaking a leg</italic>” occurred with the entity “<italic>leg of John</italic>” at time-event “<italic>yesterday</italic>” and the relationship “<italic>is in</italic>” valid between “<italic>John</italic>” and “<italic>Santa Clara Hospital</italic>” now. We use the term object to refer to entities, relationships, events or facts, undistinguishably.

Object Oriented Real-Time Database Design and Hierarchical Control Systems

This paper discusses aspects related to the integration between Database Management Systems and Hierarchical Real-Time Control Systems. A method that can be applied to the design and prototyping of both realtime control systems and real-time databases is introduced. This method is based on an extension of High-level Petri nets, named G-Nets, allowing object oriented modeling and evolutionary systems development. An example based on a flexible manufacturing system is also presented.

Extending SOA with Semantic Mediators

Mediators are critical for service scenarios, since providers and consumers frequently have opposite goals, e.g. to maximize profit with minimal resource (provider perspective) against to maximize satisfaction with minimal cost (consumer perspective). Nonetheless, semantic mediation is not explicitly taken into account in the Service Oriented Architecture (SOA). In this paper, it is presented an extension of SOA which includes the mediator as first-level entity, besides the client, the provider, and the registry of the services. The assignment of semantics to information that is processed by the mediator through ontologies, and the formalization of mediators behavior are included among the advantages of the proposal.