The Nine Comments on the RCC Theory

This paper comments on nine aspects of the Region Connection Calculus (the RCC theory) with conclusions as follows: (1) regions in the RCC theory shall not be points; (2) the identical relation is a deviation from its classic usage; (3) the ι operator is un-determinate; (4) it is unclear about the notion of region in the theory; (5) atomic regions have zero thickness, instead of non-zero thickness as is assumed in the theory; (6) there is room for simple distance relations in the RCC theory; (7) there is no room for the congruence relation in the theory; (8) properties of the connection relation are not sufficiently characterized; (9) the connection relation formalized in the theory is not primitive for spatial representations in general.