On the Desirability and Limitations of Linear Spatial Database Models

A general linear spatial database model is presented in which both the representation and the manipulation of non spatial data is based on rst order logic over the real numbers with addition We rst argue the naturalness of our model and propose it as a general framework to study and compare linear spatial database models However we also establish that no reasonable safe extension of our data manipulation language can be complete for the linear spatial queries in that even very simple queries such as deciding colinearity or computing convex hull of a nite set of points cannot be expressed We show that this fundamental result has serious rami cations for the way in which query languages for linear spatial database models have to be designed