Qualitative Extents for Spatio-Temporal Granularity
John G. Stell · Spatial Cognition and Computation · 2003
The concepts of everywhere and somewhere generate three spatial extents: (1) everywhere, (2) somewhere but not everywhere, and (3) nowhere. These three extents can be used for the granular description of spatial regions. When spatio-temporal regions are considered there are two additional concepts: always and sometimes. The interaction of the four concepts can be used to produce various systems of spatio-temporal extents. The paper shows that if we want to give granular descriptions of spatio-temporal regions, then the system of extents needs to be chosen carefully. A suitable system of eleven spatio-temporal extents is identified, and a simplified system of six extents is also described. The systems of extents presented here are important in that they will allow various structures and theories understood only in a purely spatial context to be generalized to the spatiotemporal case.