KICS: Representation of Regulatory Information and the Use of Case-Based Reasoning to Support the Relaxation Process

This thesis presents a case-based reasoning system (KICS) which can assist domain experts in interpreting building regulations in relaxation cases. In traditional legal decision support systems, it has been regarded as natural to represent legal rules in statutes in terms of If-Then decision rules and to link these rules to a separate casebased reasoning system for handling cases. However, we take a view that legal rules in the statutory regulations are the results of accumulation and generalisation of rulings made in case histories and this has led us to a uni ed case-based approach to handle both statutory regulations and cases. First, we propose a uni ed case-based model of regulatory information. In this model, regulatory information, i.e., legal rules from statutes and precedent cases, are represented as models, and interpretation hierarchies of legal rules are represented as abstraction hierarchies of models in the Model Knowledge Base. Actual cases are stored in the Case Library together with arguments debated. Background domain knowledge used in classifying input cases are represented as semantic networks and heuristic rules in the Domain Knowledge Base. Second, we propose to use case-based reasoning to access and maintain regulatory information. Models relevant to the input case are retrieved by identifying the level of abstraction at which the input case is described and by selecting models similar to the input case. If the input case is not compliant with the retrieved models, principles behind retrieved legal rules and previous similar cases are explained to the user and ask whether relaxation can be granted. Decision on relaxation is made by the user, and rulings made in cases in which relaxation is granted are acquired by generalising them and (if possible) combining them with existing models in the abstraction hierarchies. Third, we describe the results of the evaluation of the prototype system carried out using the Scottish building regulations and 22 appeals cases from the Building Directorate of The Scottish O ce. The proposed framework has been successfully used to process 22 appeal cases and has been demonstrated to be a exible and e cient indexing mechanism. The evaluation with real-world cases has also suggested that, as the system moves towards the real-world environment, the retrieval algorithm needs to be re ned and supplied with more domain-speci c knowledge. The case-based approach proposed in this thesis provides a representational framework in which legal rules at various abstraction levels including principles or legislative intentions can be explicitly represented and used to provide explanation. It also allows both statutes and precedent cases to be integrated in one knowledge representation scheme. Therefore, up-to-date interpretation of regulations can be maintained by accumulating new rulings along with existing legal rules. ii Acknowledgements I am most grateful to Dave Robertson, my rst supervisor, who suggested to apply case-based reasoning to the domain of building regulations, and who has been generous with his advice and suggestions and also patient with my English. I am also grateful to John Lee, my second supervisor, who has shown great interest in my research and has always found time for comments on my work. Part of the work was done while I was still working as a full-time Research Assistant in the SERC Authoring Project (Grant Number: GR/F/89022). I thank the members of the project, Chris Tweed, Dave Robertson, Andrew Casson, Paul Chung, Jussi Stader, Alistair Watson, Mike Ward, Jarlath Trainer and David Stone, and the SERC for their support. My thanks also go to the British Council in Korea for supporting my work. I am indebted to members of KBS group in the department, Alberto Castro, Peter Funk, Mandy Haggith, Jane Hesketh, Weiru Liu, Edjard Mota, Namseog Park, Maria Vargas-Vera and Wamberto W. Vasconcelos. I am also indebted to The Scottish O ce for allowing appeal cases to be used in this research. However, any views expressed in this thesis about the Scottish building regulations are those of the author alone. Finally, I would like to dedicate my thesis to my parents. iii Declaration I hereby declare that I composed this thesis entirely myself and that it describes my own research. Soon-Ae Yang Edinburgh May 31, 1995 iv