1630	 Computer Representation of Planar Regions by Their Skeletons	 Any region can be regarded as a union of maximal neighborhoods of its points and can be specified by the centers and radii of these neighborhoods this set is a sort of skeleton of the region. The storage required to represent a region in this way is comparable to that required when it is represented by encoding its boundary. Moreover the skeleton representation seems to have advantages when it is necessary to determine repeatedly whether points are inside or outside the region or to perform set-theoretic operations on regions.
