The difference between the cartographic and the model view is the possibility for database manipulation in the later case, independent from graphic representation. This need becomes urgent in view of the design of future GISs in which the user will interact with the geo- objects in the easiest possible way, without need to know the details of internal representations. Another issue is the prioritization of topological relations between spatial objects, knowing that some topological relations may be affected by generalization. Finally, an additional issue of model-oriented generalization was raised in the temporal domain. For example, higher levels of temporal abstractions might be useful for analyzing phenomena in a broader temporal context.
Temporal generalization increases the dimensionality of the problem space.
We have to consider the problems of object identity and changes not only in the spatial and attribute domains, but also in the temporal domain. Interestingly, the distinction between model and graphics brings about the issue of database for multi- purpose applications. The fourth and last session was dedicated to quality and operational issues. Everybody agreed that part of the future research must concentrate on evaluation and validation of existing tools, rather than trying to re-invent the wheel. A set of quantitative and qualitative evaluation specifications must be developed, in relation to the production needs to mapping agencies.