THIS PAPER is about the complexity of reasoning about cardinal directions in 2D space. By cardinal directions, we mean North, South, East, West and the intermediate directions Northeast, Northwest,… (More)

What is a qualitative calculus? Many qualitative spatial and temporal calculi arise from a set of JEPD (jointly exhaustive and pairwise disjoint) relations: a stock example is Allen’s calculus, which… (More)

It has now been clear for some time that for many qualitative spatial or temporal calculi, for instance the well-known RCC8 calculus, the operation of composition of relations which is used is… (More)

Ladkin and Maddux [LaMa87] showed how to interpret the calculus of time intervals defined by Allen [AZ2831 in terms of representations of a particular relation algebra, and proved that this algebra… (More)

This paper proves a key result in the maximality proof of ORD-Horn relations, namely, the fact that any subclass of Allen's algebra which contains all atomic relations, is closed under conversion,… (More)

Temporal and spatial reasoning is a central task for numerous applications in many areas of artificial intelligence. For this task, numerous formalisms using the qualitative approach have been… (More)