Abstract

A triangulation of a finite point set A in $\mathbb{R}^d$ is a geometric simplicial complex which covers the convex hull of $A$ and whose vertices are points of $A$. We study the graph of triangulations whose vertices represent the triangulations and whose edges represent geometric bistellar flips. The main result of this paper is that the graph of triangulations in three dimensions is connected when the points of $A$ are in convex position. We introduce a tree of triangulations and present an algorithm for enumerating triangulations in $O(log log n)$ time per triangulation.

Highlights

  • Given a finite set of points in IRd, a triangulation of A is a geometrically realized simplicial complex which covers the convex hull of A and has their sets of vertices contained in A

  • We are interested in a notion of elementary changes between triangulations of A known as geometric bistellar flips

  • De Loera et al [dLSU99] mentioned a possibility that graph of triangulations can be disconnected in three dimensions even if the points of A are in the vertices of a convex polytope

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Summary

Introduction

Given a finite set of points in IRd, a triangulation of A is a geometrically realized simplicial complex which covers the convex hull of A and has their sets of vertices contained in A. De Loera et al [dLSU99] studied how many bistellar flips could a triangulation of configurations with n points in IRd have? 1) any triangulation of n points in the plane has at least n 3 bistellar flips, and ¢. Santos [San00] constructed sequences of triangulations of point configurations in IR3 with n2 £ 2n £ 2 vertices and only 4n 3 geometric bistellar flips. De Loera et al [dLSU99] mentioned a possibility that graph of triangulations can be disconnected in three dimensions even if the points of A are in the vertices of a convex polytope. The main result of this paper is the answer to their question: the graph of triangulations of n points in convex position in IR3 is connected.

Triangulations and Flips
Graph of triangulations
Existence of an improving flip
There exists a vertex of A
Enumeration of triangulations
Findings
Conclusion
Full Text
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