A Complete Analysis of Tractability in RCC-8

Abstract

In Chapter 6 we identified Ĥ8, a maximal tractable subset of RCC-8 that contains all base relations and for which path-consistency is complete for deciding inconsistency. It is, however, not clear whether Ĥ8 is the only such set or whether there are other maximal tractable subsets of RCC-8 that contain all base relations. There are at least two reasons why answering this question is important. First of all, without a complete analysis of tractability there are interesting subsets of RCC-8 for which it is unknown whether reasoning over these sets is tractable or NP-complete. Secondly, if new tractable subsets can be identified, these can be used to further enhance efficiency of reasoning over RCC-8.