Compromised Updates in Labelled Databases

This paper presents a logical system, CIULDS, as a labelled realization to our approach of Compromising Interfering Updates. The approach proposes a method for handling logically con icting inputs into knowledge bases, via restricting their consequences. The main idea is to update the database with as many consistent consequences of the inputs as possible, in the case that the inputs themselves are not allowed to be kept in it. And in the case that a revision applies, the idea is to keep as many as possible of the consistent consequences of the retracted sentences as a compromise. The reconciliation of con icting inputs follows some speci ed postulates for compromised revision. CIULDS is based on the Labelled Deductive Systems framework (LDS). In CIULDS we take advantage of LDS's labelling facility, to control the derivation process of the compromised consequences. We embed in the labelling propagation conditions, which act on the inference rules, part of the control mechanism for the compromised approach. This mechanism helps the update operations to perform the reconciliation of con icting inputs. The update operations invoke a speci c revision method, which applies some compromising criteria for achieving the revised labelled database, whenever con icts arise. In this paper, we present brie y our main motivations and we introduce the speci cation of our approach, for the case of database updates. We present CIULDS, by decribing informally its main features and de nitions. Finally, we summarize the system's main properties.