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A first order phase transition for lower tails in sparse random graphs
Abstract
We study the graphon variational problem that governs lower tail large deviations of the number of copies of a fixed nonbipartite graph H in a sparse Erdős--Rényi random graph. Our main new insight is that any non-constant minimizer of the variational problem exhibits a discontinuous jump away from the constant graphon. We deduce that the replica-symmetric and symmetry-breaking regimes are separated by a single critical parameter and that the phase transition is first order. In the supercritical regime p ≫ n−1/m2(H), we transfer these results to the conditioned random graph, showing that the edge density is a discontinuous order parameter and that the conditioned graph concentrates in cut distance near the full minimizer set.
Related
BibTeX
@misc{chin2026first,
title = {{A first order phase transition for lower tails in sparse random graphs}},
author = {Byron Chin},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27457},
eprint = {2610.27457},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27457},
}
RIS
TY - UNPB
TI - A first order phase transition for lower tails in sparse random graphs
AU - Byron Chin
PY - 2026
DA - 2026/10/20
PB - arXiv
DO - 10.48550/arxiv.2610.27457
UR - https://arxiv.org/abs/2610.27457
AB - We study the graphon variational problem that governs lower tail large deviations of the number of copies of a fixed nonbipartite graph H in a sparse Erdős--Rényi random graph. Our main new insight is that any non-constant minimizer of the variational problem exhibits a discontinuous jump away from the constant graphon. We deduce that the replica-symmetric and symmetry-breaking regimes are separated by a single critical parameter and that the phase transition is first order. In the supercritical regime p ≫ n^−1/m_2(H), we transfer these results to the conditioned random graph, showing that the edge density is a discontinuous order parameter and that the conditioned graph concentrates in cut distance near the full minimizer set.
ER -