Fungwacharakorn, Wachara; Tsushima, Kanae; Satoh, Ken
Abstract: When literal interpretation of statutes leads to counterintuitive consequences, judges, especially in high courts, may identify counterintuitive consequences and revise interpretation of statutes. Hence, researchers have studied revisions for computational legal representation. In this paper, we consider a normal logic program for a computational legal representation and a revision of a normal logic program based on legal debugging and closed world specification. Generally, studies on revision usually consider minimal revision to reflect limitation of judges’ legislative power. However, those studies tend to focus on minimizing operations on rules rather than effects on legal interpretations, which vary among cases. This paper presents a new kind of minimality to support minimizing such effects by considering semantics changed by a revision. Firstly, we introduce semantics of a rule-base and a difference of semantics. Then, we relax the definitions for the sake of flexibility and define a new dominant-based minimal revision and a method to obtain it. After that, we compare our dominant-based minimal revision with a syntax-based minimal revision in Theory Distance Metric. The comparison shows that a syntax-based minimal revision may cause extra semantics changes compared to a dominant-based minimal revision, especially when an original program contains multiple conditions. We discuss that such extra semantics changes can be considered as the changes unintentionally caused by a syntax-based minimal revision. Hence, legal reasoning systems can take the advantage by confirming intentions of such extra semantics changes with users.