Semantic hierarchies and abstractions in conceptual schemata

A conceptual schema is a clear, easy to understand and exact representation of the semantics of an underlying universe of discourse. The role of such schemata in the specification and design of information bases is now widely recognized. However, in “real life” applications, it is often the case that the size of the conceptual schema exceeds the limit above which it is necessary to have an abstraction mechanism available, as otherwise it would become difficult to understand.In this paper, we present several concepts and heuristic procedures which allow for semantic modularization of a conceptual schema, thus providing a concise representation, using different degrees of abstraction and/or viewpoints, of a schema of any size.     

Verification of conceptual schemata based on hybrid object-oriented and logic paradigm

Contemporary conceptual modelling languages are concerned with the representational adequacy of knowledge about a universe of discourse and with the efficient organization of this knowledge in structures that help overcome the problems of size and complexity in the modelled reality. In the paper it is argued that a conceptual modelling language should also facilitate the verification of captured requirements by exercising the conceptual schemata derived from the use of such a language. A conceptual modelling language is presented that is based on a hybrid representation scheme that makes use of object-oriented and logic approaches, and it is shown how this language can be used to verify requirements during the development of information systems.     

A conceptual model for the logical design of temporal databases

Although widely advocated as a tool for the conceptual modelling of data, the Entity-Relationship (E-R) model [4] and its extensions are generally lacking in constructs to model the dynamic nature of the real world, making them inadequate for designing temporal databases. This research first extends the E-R model to a Temporal Event-Entity-Relationship Model (TEERM), by introducing events as an additional construct. Second, a method is proposed for mapping this conceptual model into a temporal relational model for the logical design of temporal relational databases with a corresponding set of integrity constraints. The model is illustrated with an example and evaluated using a set of criteria proposed by ^{Batini et al. [2]}. The model appears to be expressive, simple and easy to use, and should, therefore, aid the temporal database design process significantly.     

结构图ETL概念模型的设计方法

ETL过程是数据仓库获得高质量数据的重要环节,是任何数据仓库工程不可缺少的成功因素。为了便于ETL过程的设计和维护,降低ETL过程的设计、维护代价,提出一种基于结构图的ETL概念模型设计方法,给出一个用于描述ETL过程的模型,并基于CWM完成用以存储元数据的ETL元模型的设计。通过图形化ETL过程中的元素和关联,该模型清晰直观地反映了各个源数据库与目标数据仓库的内部结构和组成、数据的来源与流向、源数据和目标数据之间的映射和转换关系,辅助设计人员更好地进行ETL过程的设计和编码实现,使整个ETL的设计与维护过程更加方便、灵活、有效。     

Design of statistical databases: A methodology for the conceptual step

The aim of the conceptual step in database design is to describe data involving in the application in a formal and abstract way, without any concern to the specific model and language chosen for the implementation. In statistical applications, data are described at different levels of aggregation, from elementary facts of the reality to complex aggregations such as classifications, time series, indexes. The paper describes a methodology for conceptual design of statistical databases that provides the designer suitable strategies for defining such different levels of aggregation starting from user requirements, and checking the completeness, coherence and minimality of the conceptual schema at the different levels. The methodology makes use of two data models for the representation of data: for elementary data the Entity-Relationship model, widely used in database applications, and for summary data a new model is proposed, designed to be an effective trade-off between expressive power and simplicity of use.     

From conceptual models to schemata: An object-process-based data warehouse construction method

Data warehouse modeling is a complex task, which involves knowledge of business processes of the domain of discourse, understanding the structural and behavioral system's conceptual model, and familiarity with data warehouse technologies. The suitability of current data warehouse modeling methods for large-scale systems is questionable, as they require multiple manual actions to discover measures and relevant dimensional entities and they tend to disregard the system's dynamic aspects. We present an Object-process-based Data Warehouse Construction (ODWC) method that overcomes these limitations of existing methods by utilizing the operational system conceptual model to construct a corresponding data warehouse schema. We specify the ODWC method, apply it on a case study, evaluate it, and compare it to existing methods.     

Enriching the conceptual basis for query formulation through relationship semantics in databases

The rapid increase in end-user computing calls into question the suitability of existing database query languages (DBQLs). Because the typical DB end-user is not a DB specialist, it is essential that DBQLs use concepts that are as close as possible to those in the end-users’ cognitive mental model and adopt interface techniques that are suited to end-users’ abilities. Concept-based query languages are well suited for this. This realization has motivated further research in conceptual, or semantic, query approaches. However, the primary focus in this field has been on semantic query optimization, not on query formulation. In this study, we address ourselves to the problem of formulation of queries using concepts. We propose a concept-based query language, called the conceptual query language (CQL), which allows for the conceptual abstraction of database queries and exploits the rich semantics of data models to ease and facilitate query formulation.The CQL approach uses the relationship semantics of semantic data models to render transparent the technical complexities of existing DB query languages. Association semantics are also used to automatically construct query graphs and pseudo-natural language explanations of queries, and to generate SQL codes. A set theoretic formalism for conceptual queries is developed and used. This paper discusses the design of CQL, its expressive power, its implementation, and the strategies for CQL query processing. The implementation of a CQL prototype is briefly discussed in this paper. User experiments were carried out extensively and showed the advantage of CQL over alternative languages such as SQL.     

A compiler for parsing schemata

We present a compiler that can be used to automatically obtain efficient Java implementations of parsing algorithms from formal specifications expressed as parsing schemata. The system performs an analysis of the inference rules in the input schemata in order to determine the best data structures and indexes to use, and to ensure that the generated implementations are efficient. The system described is general enough to be able to handle all kinds of schemata for different grammar formalisms, such as context‐free grammars and tree‐adjoining grammars, and it provides an extensibility mechanism allowing the user to define custom notational elements. This compiler has proven very useful for analyzing, prototyping and comparing natural‐language parsers in real domains, as can be seen in the empirical examples provided at the end of the paper. Copyright © 2008 John Wiley & Sons, Ltd.     

Linguistic decision schemata for intelligent robots

High-level decision making can be performed on a special purpose hierarchically structured computer with multiprocessing capabilities. The components of such a system, called decision schemata, utilize a concatenation of multielement strings of command with feedback information as an input and they map it into an output string that has the highest probability of minimizing an appropriate cost function. They are structured to process information in a decreasing order of intelligence and an increasing order of precision. Such schemata have application in intelligent control of intelligent systems and robots.     

Organizational schemata of e-portfolios for fostering higher-order thinking

The information technology of online e-portfolio systems have been widely used during the past several years along with the diffusion of electronic teaching-learning systems. However, for the time being e-portfolio is viewed more as an assessment tool or a showcase tool, but less as an active learning tool. The current generic e-portfolio systems store artifacts in the chronological order on the course basis, providing few facets for active thinking. The question of how we can make e-portfolio a useful learning tool to improve students’ learning outcomes is still open to research. Among various students’ learning outcomes, higher-order thinking has become an important outcome of education. One vision of education evolution is to change the modes of thinking of students. This study is to meet the challenge of e-portfolios by investigating a significant research question: how e-portfolios can be used as a learning tool for students to foster higher-order thinking. Specifically, this study proposes an ontological approach to organizational schema of e-portfolios so that e-portfolios can be logically and dynamically organized into thinking-driven networks. The ontological schemata can serve as visible maps for the virtual e-portfolios repository shared by all teachers and students to foster higher-order thinking. A case study that implements a prototype of organizational schemata of e-portfolios demonstrates the usefulness of the proposed approach for fostering higher-order thinking.     

A method for the unification of XML schemata

Extensible Markup Language (XML) is a common standard for data representation and exchange over the Web. Considering the increasing need for managing data on the Web, integration techniques are required to access heterogeneous XML sources. In this paper, we describe a unification method for heterogeneous XML schemata. The input to the unification method is a set of object-oriented-based canonical schemata that conceptually abstract local Document Type Definitions of the involved sources. The unification process applies specific algorithms and rules to the concepts of the canonical schemata to generate a preliminary ontology. Further adjustments on this preliminary ontology generate a reference ontology that acts as a front-end for user queries to the XML sources.     

Properties of stochastic syntax-directed translation schemata

Stochastic syntax-directed translation schemata describe both the syntactic structure and the probability distribution of stochastic mappings between contextfree languages. The relationship between stochastic syntax-directed translation schemata and stochastic grammars and automata are presented by proving that a stochastic pushdown transducer can be constructed to define the same translations as a simple schema, and that the simple schema are characterized by stochastic contextfree grammars. Asymptotic properties of linear schemata are established by the theory of Markov chains. Since stochastic translations contain both input and output strings, their information content can be described. Equations are developed for both the information content and the rate of stochastic translations.     

Simplified handling of iterated term schemata

We propose an extension of primal grammars (Hermann and Galbavý, Theor Comp Sci 176(1–2):111–158, 1997), called P-grammars. Primal grammars are term grammars with a high expressive power and good computational properties. P-grammars have exactly the same properties but are more modular, more concise, and easier to use, as shown by some examples. We prove that P-grammars are exponentially more concise than primal grammars. An algorithm, called p2primal, transforming any P-grammar into an equivalent primal grammar is provided, thus making the original formalism much easier to handle from a practical point of view.