ABSTRACT
Spatio-temporal reasoning is an important part of many decisions. It is how armies know where to place gun nests, prisons know where to place cameras, firemen know where to place firebreaks, cities know where to place highways, and malls know where to place stores. Much has been written about the spatial aspect of spatio-temporal reasoning. To keep focus on the temporal part of spatio-temporal reasoning, examples will use a tower defense game. An affordance is something that affords an action. More importantly, it suggests an action. The spatial geometry is mirrored across the diagonal axis. This makes the map symmetric, but only spatially. When it comes to time, the map is strongly asymmetric. Path Gap is a spatial affordance in the sense that it is based on the length of a path. As such, it can only be used on maps where the geometry supports it.
