An isotopic invariant for planar drawings of connected planar graphs
Jan Hidders · TU/e Research Portal · 1995
In this report we will present a data structure called PLA-structure for representing the topological information of a database containing points, lines and areas in a plane.This data structure gives for every point in the database the circular alternating list of incident lines and adjacent areas that one sees as one proceeds clockwise around the point.It will be shown in this report that if we add an indication of which area is the "outside" of the drawing in the plane, the datastructure is a complete isotopic invariant.This means that the data structure contains exactly all the isotopic information of the data.The data structure is therefore interesting as an efficient data structure for spatial data that is mainly queried on its topological aspects.