Modelling Spatial Inferences in

Text understanding in a spatial domain is often seen as the construction of a mental model. In this paper we present the rst prototype of a program that realizes some of the characteristics claimed for spatial reasoning processes in mental models. Our work is based on homogeneous coordinate systems and transformation matrices. This means that a relation between two objects A and B is represented by the transformation matrix that maps the coordinate system of A onto that of B, and by constraints on the parameters of the matrix. We argue that this approach is more exible and more suitable for modelling spatial relations than qualitative approaches. While the psychological questions concerning mental models are largely skipped over, the advantages and problems of our program are discussed in more detail.