Delineating boundaries for imprecise regions

In geographic information retrieval, queries often name geographic regions that do not have a well-defined boundary, such as "Southern France." We provide two algorithmic approaches to the problem of computing reasonable boundaries of such regions based on data points that have evidence indicating that they lie either inside or outside the region. Our problem formulation leads to a number of subproblems related to red-blue point separation and minimum-perimeter polygons, many of which we solve algorithmically. We give experimental results from our implementation and a comparison of the two approaches.