Region Connection Calculus: Its models and composition table

Originating in Allen’s analysis of temporal relations, the notion of composition table has become a key technique in providing an efficient inference mechanism for a wide class of theories in the field artificial intelligence. This paper is mainly about the consistency-based composition table (RCC8 CT) of the Region Connection Calculus (RCC) raised by Randell, Cui and Cohn. First we show each RCC model is a consistent model of the RCC8 CT. Then after an exhaustive analysis we show that no RCC models can be interpreted extensionally anyway and hence give a negative answer to a conjecture raised by Bennett. All these results are given in an ‘extensional’ RCC8 composition table, where we attach to each cell entry in the RCC8 CT a superscript to indicate in what circumstances an extensional interpretation is possible.