The $d$-dimensional realisation number of a rigid graph
Abstract
Determining the number of (complex) realisations of a rigid graph for a specific choice of edge lengths is a fundamental problem in discrete geometry. In this article we provide two new tools for determining realisation numbers in arbitrary dimensions: (i) we prove that subgraph inclusion translates to realisation number divisibility; and (ii) we provide lower bounds on realisation numbers under specific graph operations in all dimensions. We use these methods to prove that every triangulated sphere with vertices has at least edge-length equivalent realisations in 3-dimensions, extending a 2-dimensional result of Jackson and Owen in the case of planar graphs. Additionally, our tools solve a family of conjectures set by Grasegger regarding how 1-extensions, X-replacements, and V-replacements affect realisation numbers.
Cite
@article{arxiv.2602.20766,
title = {The $d$-dimensional realisation number of a rigid graph},
author = {Sean Dewar and Anthony Nixon and Ben Smith},
journal= {arXiv preprint arXiv:2602.20766},
year = {2026}
}
Comments
26 pages, 7 figures