“…Some researchers have used computational geometry-based methods such as convex hull and Voronoi diagrams (Lai and Wang 1988;Traband et al, 1989;Etesami and Qiao 1990;Huang 1999). Numerical approximation of the objective function (Dhanish and Shunmugam 1991), enumeration methods and combinatorics (Ventura and Yeralan 1989;Rajagopal and Anand 1999;Hodgson et al, 1999), genetic algorithms (Lai et al, 2000), neural networks (Suen and Chang 2000), support vector regression (Prakasvudhisarn et al, 2003), etc. have been used for the determination of the zone boundaries.…”