Delaunay Triangulations with Predictions

TL;DR

This paper explores algorithms that leverage predictions of Delaunay triangulations to compute the correct triangulation more efficiently, introducing new algorithms with optimal or near-optimal performance based on different predictive models.

Contribution

It introduces novel algorithms for computing Delaunay triangulations using predictions, achieving improved efficiency under various deterministic and probabilistic assumptions.

Findings

Deterministic algorithm with $O(n + D ext{log}^3 n)$ time.

Randomized algorithm with $O(n + D ext{log} n)$ expected time.

High-probability algorithm with $O(n ext{log} ext{log} n + n ext{log}(1/ ho))$ time.

Abstract

We investigate algorithms with predictions in computational geometry, specifically focusing on the basic problem of computing 2D Delaunay triangulations. Given a set $P$ of $n$ points in the plane and a triangulation $G$ that serves as a "prediction" of the Delaunay triangulation, we would like to use $G$ to compute the correct Delaunay triangulation $\textit{DT}(P)$ more quickly when $G$ is "close" to $\textit{DT}(P)$. We obtain a variety of results of this type, under different deterministic and probabilistic settings, including the following: 1. Define $D$ to be the number of edges in $G$ that are not in $\textit{DT}(P)$. We present a deterministic algorithm to compute $\textit{DT}(P)$ from $G$ in $O(n + D\log^3 n)$ time, and a randomized algorithm in $O(n+D\log n)$ expected time, the latter of which is optimal in terms of $D$. 2. Let $R$ be a random subset of the edges of $\textit{DT}(P)$, where each edge is chosen independently with probability $\rho$. Suppose $G$ is any triangulation of $P$ that contains $R$. We present an algorithm to compute $\textit{DT}(P)$ from $G$ in $O(n\log\log n + n\log(1/\rho))$ time with high probability. 3. Define $d_{\mbox{\scriptsize\rm vio}}$ to be the maximum number of points of $P$ strictly inside the circumcircle of a triangle in $G$ (the number is 0 if $G$ is equal to $\textit{DT}(P)$). We present a deterministic algorithm to compute $\textit{DT}(P)$ from $G$ in $O(n\log^*n + n\log d_{\mbox{\scriptsize\rm vio}})$ time. We also obtain results in similar settings for related problems such as 2D Euclidean minimum spanning trees, and hope that our work will open up a fruitful line of future research.