# An upper bound on Pachner moves relating geometric triangulations

## TL;DR

This paper establishes an upper bound on the number of Pachner moves needed to relate any two geometric triangulations of closed hyperbolic, spherical, or Euclidean manifolds, enabling an algorithmic approach to manifold isometry verification.

## Contribution

It provides a bounded sequence of Pachner moves and barycentric subdivisions connecting any two geometric triangulations, based on manifold dimension, simplexes count, and edge length bounds.

## Key findings

- Bounded Pachner move sequences exist for geometric triangulations.
- Algorithm for isometry checking based on triangulation combinatorics.
- Applicable to hyperbolic, spherical, and Euclidean manifolds.

## Abstract

We show that any two geometric triangulations of a closed hyperbolic, spherical or Euclidean manifold are related by a sequence of Pachner moves and barycentric subdivisions of bounded length. This bound is in terms of the dimension of the manifold, the number of top dimensional simplexes and bound on the lengths of edges of the triangulation. This leads to an algorithm to check from the combinatorics of the triangulation and bounds on lengths of edges, if two geometrically triangulated closed hyperbolic or low dimensional spherical manifolds are isometric or not.