In this paper, we present an $\Theta (n)$ time worst-case deterministic algorithm for finding the constrained Delaunay triangulation and constrained Voronoi diagram of a simple n-sided polygon in the plane. Up to now, only an O(n log n) worst-case deterministic and an O(n) expected time bound have been shown, leaving an O(n) deterministic solution open to conjecture.

This paper presents a new approach for the following collision detection problem in the plane: Let a simple polygon P rotate at a center /spl ogr/ with constant angular velocity /spl omega/ and translate towards a set of polygonal obstacles S with constant velocity /spl nu/. Given P and S as well as their initial positions, and given also the velocities of P, determine whether or not P will collide with any element of S and report the collided elements of S if collisions occurred. An O(mn) worst-case optimal algorithm is proposed to solve this problem, where n is the number of vertices of P and m is the number of vertices of the obstacles in S.>

In this paper, we first define a new Voronoi diagram for the endpoints of a set of line segments in the plane which do not intersect (except possibly at their endpoints), which is called a bounded Voronoi diagram. In this Voronoi diagram, the line segments themselves are regarded as obstacles. We present an optimal Θ(n log n) algorithm to construct it, where n is the number of input line segments.

In this paper, we present an Ο(n log n) algorithm for finding the minimum Euclidean visible vertex distance between two nonintersecting simple polygons, where n is the number of vertices in a polygon. The algorithm is based on applying a divide and conquer method to two preprocessed facing boundaries of the polygons. We also derive an Ο(n log n) algorithm for finding a minimum sequence of separating line segments between two nonintersecting polygons.

Two planar geometric problems relating to a convex n-gon P and a simple nonconvex m-gon Q are considered.