event
Monday 03 Oct 2011: CS seminar - Modelling Spatial Change by Relations between Trees
John Stell - School of Computing, University of Leeds
Harrison 203 15:00-16:00
In many cases of dynamic spatial phenomena it is necessary to model foreground and background regions which exhibit changes over time. Such changes include splitting, where one region divides into two, and merging, where two regions become one. For example, the qualitative description of the development of wildfires would use the foreground for areas on fire and the background for
areas not on fire. Other examples would include crowds of people moving against the background of a city, and regions of land and water changing as sea levels rise.
If we restrict the spatial structure to nesting (so two regions are either disjoint or one is wholly inside the other), the changes can be modelled by a particular kind of relation between the nodes of two adjacency trees representing the initial and final configurations of the regions at two times.
There are four types of atomic relation (in addition to one representing no change): inserts, splits, merges and deletes. These can be combined by composition to yield all relations between trees that model the behaviour of nested regions. In the talk I will present some results about these "bipartite" relations, and go on to consider relations which relate edges of trees as well as nodes. These provide additional information about the boundaries of changing regions.
