Quadratic edge-statistics conjecture

Let ind(k,)\operatorname{ind}(k,\ell) denote the limiting maximum proportion of kk-vertex subsets inducing exactly \ell edges. Quadratic edge-statistics conjecture. For all pairs (k,)(k,\ell) satisfying

min{,(k2)}=Ω(k2),\min \left\{\ell, \binom{k}{2} - \ell \right\} = \Omega(k^2),

we have

ind(k,)=O(k1/2).\operatorname{ind}(k,\ell) = O(k^{-1/2}).

The conjecture concerns the correct order in the dense edge-count range. The paper notes examples with a matching lower bound of order k1/2k^{-1/2}, but the asserted universal upper bound remains open.

Sources & referencesView supporting material

Primary source

Noga Alon, Dan Hefetz, Michael Krivelevich and Mykhaylo Tyomkyn, “Edge-statistics on large graphs”, arXiv:1805.06848 (2019).

Progress summary

Refreshed
Solved

The conjecture’s claimed upper bound was proved in 2018, and no later gap or reversal was found.

The assertion appears in the 2018 literature as the dense-range part of the broader edge-statistics conjecture, attributed to Alon, Hefetz, Krivelevich, and Tyomkyn. The dense regime is now covered by published or publicly available proofs.

Known results

  • Kwan, Sudakov, and Tran (2018) proved the bound for Ω(k)(k2)Ω(k)\Omega(k)\leq \ell\leq \binom{k}{2}-\Omega(k), which includes the quadratic range.
  • A related 2018 paper established only ind(k,)logO(1)(/k)k/\operatorname{ind}(k,\ell)\leq \log^{O(1)}(\ell^*/k)\sqrt{k/\ell^*} in its stated theorem, with =min{,(k2)}\ell^*=\min\{\ell,\binom{k}{2}-\ell\}.
  • Examples attain order k1/2k^{-1/2} in some cases, showing the dense bound has the correct order.

2018 completion of the edge-statistics conjecture

The completion paper explicitly states that Kwan, Sudakov, and Tran proved the linear-to-co-linear range; combined with independent sparse-regime results, this settles the full edge-statistics conjecture and therefore the quadratic edge-statistics conjecture.

Current status (as of August 2026): The quadratic dense-range bound ind(k,)=O(k1/2)\operatorname{ind}(k,\ell)=O(k^{-1/2}) is settled; no counterexample, proof gap, withdrawal, or retraction was found.

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