Composition for Cardinal Directions by Decomposing Horizontal and Vertical Constraints

Foundations and Applications of Spatio-Temporal Reasoning (FASTR)

Volume

Papers from the 2003 AAAI Spring Symposium

Contents

In this paper, we demonstrate how to group the nine cardinal directions into sets and use them to compute a composition table. Firstly, we define each cardinal direction in terms of a certain set of constraints. This is followed by decomposing the cardinal directions into sets corresponding to the horizontal and vertical constraints. We apply two different techniques to compute the composition of these sets. The first technique is an algebraic computation while the second is the typical technique of reasoning with diagrams. The rationale of applying the latter is for confirmation purposes. The use of typical composition tables for existential inference is rarely demonstrated. Here, we shall demonstrate how to use the composition table to answer queries requiring the common forward reasoning as well as existential inference.Also, we combine mereological and cardinal direction relations to create a hybrid model which is more expressive.