Finding cliques and dense subgraphs using edge queries

Fuente: arXiv
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Main Authors: Csóka, Endre, Pongrácz, András
Format: Preprint
Published: 2023
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author Csóka, Endre
Pongrácz, András
author_facet Csóka, Endre
Pongrácz, András
contents We consider the problem of finding a large clique in an Erdős--Rényi 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 $α_{\star}(δ,\ell)$ be the supremum over $α$ such that there exists an algorithm that makes $n^δ$ queries in total to the adjacency matrix of $G$, in a constant $\ell$ number of rounds, and outputs a clique of size $α\log_{2} n$ with high probability. We give improved upper bounds on $α_{\star}(δ,\ell)$ for every $δ\in [1,2)$ and $\ell \geq 3$. We also study analogous questions for finding subgraphs with density at least $η$ for a given $η$, and prove corresponding impossibility results.
format Preprint
id arxiv_https___arxiv_org_abs_2310_06826
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Finding cliques and dense subgraphs using edge queries
Csóka, Endre
Pongrácz, András
Combinatorics
Discrete Mathematics
05C80, 05C85, 68Q87, 68W20
We consider the problem of finding a large clique in an Erdős--Rényi 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 $α_{\star}(δ,\ell)$ be the supremum over $α$ such that there exists an algorithm that makes $n^δ$ queries in total to the adjacency matrix of $G$, in a constant $\ell$ number of rounds, and outputs a clique of size $α\log_{2} n$ with high probability. We give improved upper bounds on $α_{\star}(δ,\ell)$ for every $δ\in [1,2)$ and $\ell \geq 3$. We also study analogous questions for finding subgraphs with density at least $η$ for a given $η$, and prove corresponding impossibility results.
title Finding cliques and dense subgraphs using edge queries
topic Combinatorics
Discrete Mathematics
05C80, 05C85, 68Q87, 68W20
url https://arxiv.org/abs/2310.06826