PreprintarXiv licencearXiv
The number of realisations of a random graph
Abstract
Determining the number of realisations, up to isometries, of a graph for a specific choice of edge lengths is a fundamental problem in discrete geometry. In this article we prove that, asymptotically almost surely, the d-dimensional complex realisation number for each n-vertex graph in an Erdős-Rényi random graph process is either infinite or equal to 2n−t where t is the size of the (d+1)-core; moreover this number coincides exactly with the real realisation number for such graphs. We also determine a similar formula for the number of complex solutions to the generic rank-d positive semi-definite matrix completion problem with randomly selected non-diagonal unknown entries.
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BibTeX
@misc{dewar2026number,
title = {{The number of realisations of a random graph}},
author = {Sean Dewar and Anthony Nixon and Ben Smith},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2605.18487},
eprint = {2605.18487},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.18487},
}
RIS
TY - UNPB
TI - The number of realisations of a random graph
AU - Sean Dewar
AU - Anthony Nixon
AU - Ben Smith
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2605.18487
UR - https://arxiv.org/abs/2605.18487
AB - Determining the number of realisations, up to isometries, of a graph for a specific choice of edge lengths is a fundamental problem in discrete geometry. In this article we prove that, asymptotically almost surely, the d-dimensional complex realisation number for each n-vertex graph in an Erdős-Rényi random graph process is either infinite or equal to 2^n−t where t is the size of the (d+1)-core; moreover this number coincides exactly with the real realisation number for such graphs. We also determine a similar formula for the number of complex solutions to the generic rank-d positive semi-definite matrix completion problem with randomly selected non-diagonal unknown entries.
ER -