Non-existence probabilities and lower tails in the critical regime via Belief Propagation

Fuente: arXiv
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Main Authors: Jenssen, Matthew, Perkins, Will, Potukuchi, Aditya, Simkin, Michael
Format: Preprint
Published: 2026
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author Jenssen, Matthew
Perkins, Will
Potukuchi, Aditya
Simkin, Michael
author_facet Jenssen, Matthew
Perkins, Will
Potukuchi, Aditya
Simkin, Michael
contents We compute the logarithmic asymptotics of the non-existence probability (and more generally the lower-tail probability) for a wide variety of combinatorial problems for a range of parameters in the `critical regime' between the regime amenable to hypergraph container methods and that amenable to Janson's inequality. Examples include lower tails and non-existence probabilities for subgraphs of random graphs and for $k$-term arithmetic progressions in random sets of integers. Our methods apply in the general framework of estimating the probability that a $p$-random subset of vertices in a $k$-uniform hypergraph induces significantly fewer hyperedges than expected. We show that under some simple structural conditions on the hypergraph and an upper bound on $p$ determined by a phase transition in the hard-core model on the infinite $k$-uniform, $Δ$-regular, linear hypertree, this probability can be accurately approximated by the Bethe free energy evaluated at the unique fixed point of a Belief Propagation operator on the hypergraph.
format Preprint
id arxiv_https___arxiv_org_abs_2604_04652
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Non-existence probabilities and lower tails in the critical regime via Belief Propagation
Jenssen, Matthew
Perkins, Will
Potukuchi, Aditya
Simkin, Michael
Combinatorics
Probability
We compute the logarithmic asymptotics of the non-existence probability (and more generally the lower-tail probability) for a wide variety of combinatorial problems for a range of parameters in the `critical regime' between the regime amenable to hypergraph container methods and that amenable to Janson's inequality. Examples include lower tails and non-existence probabilities for subgraphs of random graphs and for $k$-term arithmetic progressions in random sets of integers. Our methods apply in the general framework of estimating the probability that a $p$-random subset of vertices in a $k$-uniform hypergraph induces significantly fewer hyperedges than expected. We show that under some simple structural conditions on the hypergraph and an upper bound on $p$ determined by a phase transition in the hard-core model on the infinite $k$-uniform, $Δ$-regular, linear hypertree, this probability can be accurately approximated by the Bethe free energy evaluated at the unique fixed point of a Belief Propagation operator on the hypergraph.
title Non-existence probabilities and lower tails in the critical regime via Belief Propagation
topic Combinatorics
Probability
url https://arxiv.org/abs/2604.04652