Nonmonotonic Reasoning in Florid

The advantages of Florid as a deductive object--oriented database system are the rich object--oriented modeling facilities of its language Flogic. The focus of this paper is on Florid's multiple inheritance mechanism which turns out to be a useful means to adapt various examples of nonmonotonic reasoning in the object--oriented setting. 1 Introduction With Florid (F-logic reasoning in databases) [7] we present an implementation of all essential features of F-logic, a rule language for deductive object--oriented databases. In this area one is concerned with nonmonotonic reasoning in various ways. Besides the well--known problems with negation and recursion, see e.g. [2, 3], an important issue is the inheritance of methods. Since as a distinctive feature the language allows for the unrestricted definition of class information by rules, an involved interdependence between logical deduction and inheritance takes place. Consider first the following classical example which illustrates the i..

DOOD and DL -- Do We Need an Integration?

Description logics and deductive object oriented databases provide a similar view on the structure of an application domain, but rely on quite different reasoning paradigms. Recently their combination is dicussed. However, such a general solution is not at hand yet. Fortunately, a thorough investigation of the application and a thoughtful decision for an advanced system using the appropriate of both reasoning paradigms may also lead to a concise and simple implementation, even in cases which at first sight seem not to fit in the declarative framework. Here we describe our experiences with a linguistics problem. 1 Introduction Over the last years the relationship between advanced database models and description logics (DL) has been increasingly discussed. On the database side deductive object oriented database (DOOD) languages added to traditional database techniques a rich structure as well as rules to describe intensional information. On the other side applications of DL have to han..

Towards Efficient Evaluation of Methods by Reduction

Bottom-up evaluation of DOOD programs is improved by adding functional reduction as call--by--need computation for scalar methods. To that aim methods, conceived as a functional language, have to satisfy certain properties, like uniqueness and directed use from call to result. In this paper we propose declarative and operational semantics of such methods, formalize the required properties, and show the integration of reduction and bottom-up evaluation. In an experiment this approach shows a better performance than a top-down technique and magic set optimization. 1 Introduction During the last decade much research has been done to develop logics for object--oriented databases. Typically such approaches comprise object--identity, methods, classes, and inheritance. Moreover, in advanced languages like F-logic [4, 8], schema and data are handled at a uniform level, enabling among others, the data--dependent definition of classes. If such a logic is used as a deductive rule language, due t..

[email protected] - Net-based Distance Education in the Traditional University

E-learning will not inevitably cause a revolution of the traditional university. On the contrary, it is not clear whether multimedia and network technology will find its place in the university to the profit of the students. We discuss various methods and techniques and propose best practices, which can succeed under the specific conditions of a traditional university

Institut fur Informatik, Albert-Ludwigs-Universitat D-79110 Freiburg, Germany e-mail:

Florid is a deductive object--oriented database system relying on F-logic, which as a distinctive feature provides rich modeling facilities. In this paper we first give an overview about the language and its implementation. Furthermore, some examples illustrate advanced data modelling, particularly the solution of some nonmonotonic problems using inheritance is pointed out. 1 Introduction Florid -- F-Logic Reasoning In Databases, provides an implementation of all essential features of F-logic [8], which is a powerful language combining the advantages of deductive databases with the rich modeling capabilities of object oriented concepts (objects, methods, class hierarchies, nonmonotonic inheritance). The language is one of the most advanced in the deductive object oriented database (DOOD) area, providing a uniform handling of data and schema (class hierarchy etc.) which allows among others data--dependent schema definition by rules. Recently, several other prototypes for DOOD have been..

DOOD and DL - Do We Need an Integration?

Description logics and deductive object oriented databases provide a similar view on the structure of an application domain, but rely on quite different reasoning paradigms. Recently their combination is dicussed. However, such a general solution is not at hand yet. Fortunately, a thorough investigation of the application and a thoughtful decision for an advanced system using the appropriate of both reasoning paradigms may also lead to a concise and simple implementation, even in cases which at first sight seem not to fit in the declarative framework. Here we describe our experiences with a linguistics problem. 1 Introduction Over the last years the relationship between advanced database models and description logics (DL) has been increasingly discussed. On the database side deductive object oriented database (DOOD) languages added to traditional database techniques a rich structure as well as rules to describe intensional information. On the other side applications of DL have to han..

Tutored Assignments Going Online

INTRODUCTION Today, many European universities take first steps to expand their traditional program by more flexible offers, allowing for studies less dependent from time and space restrictions. With the widespread use of powerful multimedia computers and broadband networks students of all disciplines and levels will not content themselves with a simple on-campus lecture room scenario. Consequently, though the basis of traditional universities will remain traditional full-time campus studying, those institutions will have to offer more and more courses in distance mode over the internet in the near future. However, as a closer look to the large number of projects and activities reveals, universities will not be able to develop a substantial amount of courses by programming training modules. Quite too often the time and personnel needed to produce courseware with authoring software is extremely underestimated and therefore simply no resources are left to tackle the remaining tasks of