This is a Java-applet to visualize the calculation of extensions for default theories in Default Logic, a special logic to represent uncertain (or "default") knowledge. This logical formalism has been introduced by Reiter in 1980 (Reiter, R., A Logic for Default Reasoning. Artificial Intelligence, 13:81-132, 1980.), as an example for nonmonotonic reasoning.
The applet has been written by Michael Fink and Axel Polleres as a tutoring tool supporting the lecture "Wissensbasierte Systeme" at the Vienna University of Technology. This is a lecture for advanced students of computer science and logic.
The aim of this demonstration is to make the fixed point method presented in the lecture clearer to the students, as the exams have shown that there are often problems in understanding this topic.
A manual will soon be available here, meanwhile refer to the short online-help.
The simulation applet needs a Java 1.1 capable browser (e.g. Netscape version 4.06 or higher, or Hotjava); make sure you have enabled Java-support.
Click here to start.