On the Methods of Handling Contradictory Knowledge

Abstract

This study presents how to deal with knowledge when it includes contradiction. We propose the ways to reject contradiction and decide a true interpretation as correct as possible by clearing the cause of contradiction. In this paper, we assume two reasons why contradiction is occurred. For one reason, it occurs due to erroneous information from transmitters which sometimes provide wrong information. Another is circumstances are always changing, the change of true interpretation causes contradiction. We define these models, and decide true interpretation or construct consistent knowledge by calculating transmitters' error rates or interpretation changing rates. Further, we consider this field from our point of view. There are many studies in this field including belief revision, belief update, combining theory and multisource reasoning. These studies can be dividbd into two groups. One is semantics dependent problem, which is mainly based on minimal change principle. The other is syntax dependent problem, which is chiefly based on maximal consistent princible. Either of them does not consider what circumstance they should be applied to, and what they guarantee. In this paper, we can classify and evaluate past various works by our model, and clarify the meanings what they intend.