Using an ontology for guiding natural language interaction with knowledge based systems

Résumé

Since the 1980s, knowledge based systems (KBSs), programs that use knowledge to model situations and solve problems, have spread throughout industry, finance and science. Human communication with these systems deals with complex concepts and relationships that are not present in other software applications. Allthough the natural language (NL) is especially appropriate for expressing these concepts, there are not many KBSs incorporating NL interfaces. The main reasons for this are problems of efficiency in NLI performance, lack of adequacy to the communication needs of the applications and the high cost of developing and maintaining them. The aim of this thesis is to study how the communication process and engineering features can be improved in NL interaction with KBSs. This study has been focused on the efficient and reusable representation of the knowledge involved in NL communication with KBSs. GISE (Generador de Interfaces a Sistemas Expertos), a system supporting NL communication with KBSs has been developed. This system adapts the general linguistic resources to application requirements in order to automatically obtain application-restricted grammars. The main issue of the system design is a separate and reusable representation of all types of knowledge involved in communication with KBSs. This knowledge consists of the application knowledge appearing in the communication, the tasks of communication, the linguistic knowledge supporting their expression and the general relationships between conceptual knowledge and its linguistic realization. Three general bases were designed to represent all this knowledge : the Conceptual Ontology (CO), the Linguistic Ontology (LO) and a set of control rules. Conceptual knowledge is represented in the CO. This conceptual knowledge includes domain and functionality issues. All knowledge required to model the applications as well as the description of all possible communication acts is provided in the CO. The CO is the skeleton for anchoring the domain and the functionality of the applications. The complexity of KBS performance makes a formal and explicit representation of their domain and functionality necessary. The general linguistic knowledge needed to cover the expression in NL of the tasks the system performs is represented by means of the LO and a set containing all possible realizations of the application terms. The LO is domain and application independent. The control information to relate the general linguistic knowledge to conceptual application knowledge in order to generate the application-restricted grammars is represented by a set of production rules. The modular organization of the relevant knowledge into separate data structures provides great flexibility for adapting the system to different types of applications and users. The grammars generated by GISE use expressive and precise language tuned to the application and adapted to the evolution of the communicative process. A menu-system to guide the user in introducing the NL is integrated into the GISE interface. GISE has been applied to a couple of applications: SIREDOJ, an ES in law and a railway communication system.