4: Expert-System-Development Tools

The process of knowledge acquisition and knowledge engineering is intensive and time-consuming. In theory expert systems can be developed using conventional programming languages, such as FORTRAN, PASCAL, etc . This is, however, a very tedious task. Therefore, it is not surprising that tools have been developed that can support the knowledge engineer. Separate tools now exist to support the knowledge acquisition and to support the implementation. Tools of the latter category are commercially available and they are described in section 4.2. During the last few years so many of these tools have become available that the choice of an appropriate tool has become an issue on its own. This aspect is discussed in section 4.3. Tools to support knowledge acquisition are still mostly at the research stage. Since the acquisition of knowledge is the main bottleneck in developing expert systems, it can be expected that these tools will become more generally available in the near future. The present state of the art is described in section 4.4. The ID3 algorithm, which can be seen as a special kind of knowledge-acquisition tool, is described in chapter 7.