To compute the fuzzy set membership value in Boundary(Ãl), we create Delaunay
Triangulation whose nodes are comprised of any vertices on core, 0.5-cut
boundary, and exterior. The membership value is obtained by intersecting a vertical
line with the plane defined by the three nodes of the triangle (Figure 4.7). In
Figure 4.7, any location within this plane is guaranteed to have a fuzzy set membership
value between 0.5 and 1