DESS is an expert system shell that was written to accompany a course on Knowledge-Based Systems at the University of Aberdeen. It demonstrate some of the basic concepts of expert system technology, including:

• forward chaining;
• backward chaining;
• tracing information;
• explanations;
• frames, with subclass hierarchies;
• reasoning with uncertainty, using a certainty factor model.

DESS is written in Prolog, and the binaries that can be downloaded from this page have been compiled using SWI-Prolog (version 5.6.21). These binaries are stand-alone executable programs that can be used without any additional software being installed (including SWI Prolog).

Documentation

• User Manual

Binaries

Operating system	Processor type	Date compiled
Linux 2.6.9-34.ELsmp	i686	2006-10-12	Download
SunOS 5.9	sparc	2006-10-12	Download

Examples

Some of the example knowledge bases from the User Manual are available on-line:

• Chapter 2: Reasoning with Facts
  • weather example
  • creatures example
• Chapter 3: Object-Attribute-Value Triples
  • nationality example
  • creatures example
  • arithmetic expressions and comparisons
  • multi-valued attributes
• Chapter 4: Frames
  • creatures example
  • procedural attachment
• Chapter 5: Uncertainty
  • certainty factors
  • mycin example
• Chapter 6: Reaction Systems
  • bagger example