A hybrid representation of vague collections for distributed object management systems

An important characteristic of distributed object management systems is tha t due to network or machine failure, the environment may become partitioned into subenvironments that cannot communicate with each other. In some appl ication scenarios, it is important that the subenvironments remain operable even in this case. In particular, queries should be processed in an approp riate way. To this end, the final and all intermediate results of a query i n a distributed object management system must be regarded as potentially va gue. In this paper, we propose a hybrid representation for vague sets and v ague multisets designed for this application context. The representation co nsists of an enumerating part, which contains the elements we could access during query processing, and a descriptive part, which describes the releva nt elements we could not access. We introduce Propagation Rules which can b e used to minimize the vagueness of a query result represented in this hybr id way. The main advantage of our approach is that the descriptive part of the representation can be used to improve the enumerating part during query processing.