Carpentier's motif-counting conjecture for community recovery in the stochastic block model

From papers

Let G=(V,E)G=(V,E) be a connected graph with (v1,v2)E(v_1,v_2)\notin E. For any partition of VV into \ell groups in which v1v_1 and v2v_2 belong to the same group, let EE^{\neq} be the set of edges of EE joining distinct groups, and set

r:=EV2.r:=\frac{|E|}{|V|-2}.

Carpentier's motif-counting conjecture. If

Er(1),|E^{\neq}|\geq r(\ell-1),

for every such partition, and if qn1/rq\asymp n^{-1/r} and λlogq1logn(K)\lambda\geq_{\log}q^{1-\log_n(K)}, then the communities in the stochastic block model can be recovered by an algorithm based on PGP_G, the count of occurrences of the motif GG.

The conjecture identifies a sufficient combinatorial condition on a motif for counting its occurrences to achieve community recovery in the regime with more than n\sqrt n communities. The supplied text does not state whether this claim has been proved or disproved.

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Primary source

Alexandra Carpentier, Christophe Giraud and Nicolas Verzelen, “Phase Transition for Stochastic Block Model with more than n Communities (II)”, arXiv:2511.21526 (2025).

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