Removing Degeneracies by Perturbing the Problem or the World

Overview & Synopsis

We describe two problem-specific approaches to remove geometric degeneracies that we call {\it perturbing the problem} and {\it perturbing the world}. Using as our primary examples 2-d and 3-d Delaunay triangulation with Euclidean and polygonal metrics, we show that these approaches lead to relatively simple and efficient perturbations of the points that do not depend on a fixed ordering or index. Thus, they produce canonical output, which is important for producing test suites and verifiers for randomized or dynamic geometric algorithms.