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arXiv · 2310.06826

Finding cliques and dense subgraphs using edge queries

Endre Csóka·András Pongrácz
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Abstract

We consider the problem of finding a large clique in an Erd\H{o}s--R\'enyi random graph where we are allowed unbounded computational time but can only query a limited number of edges. Recall that the largest clique in $G \sim G(n,1/2)$ has size roughly $2\log_{2} n$. Let $\alpha_{\star}(\delta,\ell)$ be the supremum over $\alpha$ such that there exists an algorithm that makes $n^{\delta}$ queries in total to the adjacency matrix of $G$, in a constant $\ell$ number of rounds, and outputs a clique of size $\alpha \log_{2} n$ with high probability. We give improved upper bounds on $\alpha_{\star}(\delta,\ell)$ for every $\delta \in [1,2)$ and $\ell \geq 3$. We also study analogous questions for finding subgraphs with density at least $\eta$ for a given $\eta$, and prove corresponding impossibility results.

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Endre Csóka, András Pongrácz. 2023-10-10. Finding cliques and dense subgraphs using edge queries. https://arxiv.org/abs/2310.06826

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