PREPROCESSING QUERIES WITH SPATIAL CONSTRAINTS

This paper discusses strategies for pre-processing spatial queries before executing them in a geographic database. A computational method has been devised, which is capable of assessing whether or not a spatial query is consistent, i.e., that its constraints are free of any self-contradictions. If the query is inconsistent, it can be rejected immediately without a need to process it in the database. The query evaluation is based on algebraic properties of spatial relations such as symmetry, converseness, transitivity, and composition, and it employs constraint propagation in a constraint network to detect conflicts. Examples are given for how this method works for spatial queries with constraints about topological relations, for which a comprehensive algebraic formalization exists.