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Computer Science Dept. I Research



Competitive Motion Planning

We consider ground tasks of autonomous systems in unknown environments such as exploring a room or finding a target. In the presence of incomplete information it is impossible to avoid detours so we develop strategies to approach optimal solutions. If the ratio of the costs of a strategy and the costs of the optimal solution does not exceed a fixed factor C the strategy is called competitive with factor C. A strategy is appropriate if it guarantees a suitable competitive factor. The factors are either proved with analytic means or determined experimentally.

This project is supported by the Deutschen Forschungsgemeinschaft since 1995 and is part of the DFG-research cluster efficient algorithms for discrete problems and their applications.


Document Design

We develop a system to support the design of electronic documents. The system consists of two major parts, a design editor and a design compiler.

design editor
With the design editor users specify interactively the design of electronic documents.
design compiler
The design compiler reads the design specification and an electronic document and produces the input for a formatting system.

We look for a minimal set of design specifications that allow to specify all desired design attributes. We also investigate a user interface that is simple enough to be easily used by non computer experts, because document designers usually are artists.

A closer look has been taken at the design attributes that deal with the pagination of a document. Today's simple pagination algorithms have influenced the attributes which a designer specifies for the pagination task. We have developed a new pagination algorithm that simplifies the specification of the pagination attributes and that computes better paginations.

As we expect the document design to be generic, that is the same design is applicable to all documents of a document class, the design specification has to deal with the syntactic document structure. To hide this complexity the design-by-example approach is used.

The system provides some example documents to the designer. The designer specifies the design of the examples and the system abstracts from the example and generates a generic design specification. To do so techniques from case based reasoning and algorithmic learning are used.

The project is a joint work with Prof. Dr. Anne Brüggemann-Klein, TU München, and Prof. Dr. Th. Ottmann, Uni Freiburg. It is possible to work on a diploma thesis in this area and it is also possible to participate in the co-operation with an industrial partner.


Voronoi Diagrams

The Voronoi diagram of n sites in the plane is a subdvision of the plane into regions of nearest neighbourhood. The region of one site consists of all points that are closer to this site than to any other site. These diagrams are important not only in computer science but also in other natural sciences. There are many variants of Voronoi diagrams, and a great number of different algorithms for their computation has been developped. We are interested in finding common properties of the different variants and to describe efficient constructive methods. Furthermore, we are working on interactive environments (Java applets) for experimenting with Voronoi diagrams and other geometric structures.

This project has been supported by the Deutsche Forschungsgemeinschaft (DFG) from 1991 to 1995.


BibRelEx

Documents in bibliographic databases are related in several ways with respect to their contents, e.g. by references, private or public links as well as annotations provided by experts like document X extends document Y with respect to aspect A. Using the example of a technical library for Computational Geometry, these contents-based relations shall be collected and made accessible for recherches. Based on the interlinked references the user shall be able to find the answer to queries like

In addition to classical full-text or catalogue-based retrieval and to hypertext navigation, visualization of and navigation in contents-based relationships is another intuitive possibility to access bibliographic databases. For the first time this allows the flexible presentation of complete stocks according to user-defined criteria.

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