Closure Properties of Classes of Spatio-Temporal Objects under Boolean Set Operations

We study a model for spatio-temporal objects, introduced by Chomicki and Revesz, in which spatio-temporal data is specified by a spatial reference object together with a geometric transformation that determines the movement of the reference object in time. We give complete results concerning closure under Boolean set operators for the different classes of spatio-temporal objects introduced by these authors (In particular, we also answer a conjecture by Chomicki and Revesz negatively). Since only few classes are closed under all set operators, we suggest that their model should be extended in order to increase its practical applicability.