Technical Diagnosis of Telecommunication Equipment - An Implementation of a Task specific Problems solving method (TDFL) using GCLA II

This paper describes an implementation of a small knowledge-based system in GCLA II. GCLA II is perhaps best described as a logical programming language, with some properties usually found among functional languages, and it includes hypothetical and non-monotonic reasoning as integral parts, which makes it easy to handle hypothetical queries, negation and AI-techniques like simulation and planning in a natural way. It also makes implementation of reasoning in knowledge-based systems (KBS) more direct than in Prolog. The application is an already existing KBS that guides a service technician in the task of diagnosing a specific device which is a measuring instrument for testing telecommunications equipment. The method used in the application is a problem solving method called TDFL. The TDFL method is a task specific problem solving method for technical diagnosis that gives strong support for knowledge acquisition. The method is adapted to cope with some features of the application. For example, it gives support for reducing the time required for observations and it handles parts that are not directly testable. This paper describes how to adjust the TDFL method to remedy some errors present in the original version; avoiding unnecessary search of the device and eliminating unnecessary confirmations. Some future extensions to both the TDFL method and the implementation are also presented; allowing the search for more than one fault and the possibility of turning the diagnosis backwards.