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Main Authors: D'Elia, Marco, Finocchi, Irene, Patrignani, Maurizio
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2511.03525
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author D'Elia, Marco
Finocchi, Irene
Patrignani, Maurizio
author_facet D'Elia, Marco
Finocchi, Irene
Patrignani, Maurizio
contents Maximal cliques play a fundamental role in numerous application domains, where their enumeration can prove extremely useful. Yet their sheer number, even in sparse real-world graphs, can make them impractical to be exploited effectively. To address this issue, one approach is to enumerate $\ell$-isolated maximal cliques, whose vertices have (on average) less than $\ell$ edges toward the rest of the graph. By tuning parameter $\ell$, the degree of isolation can be controlled, and cliques that are overly connected to the outside are filtered out. Building on Tomita et al.'s very practical recursive algorithm for maximal clique enumeration, we propose four pruning heuristics, applicable individually or in combination, that discard recursive search branches that are guaranteed not to yield $\ell$-isolated maximal cliques. Besides proving correctness, we characterize both the pruning power and the computational cost of these heuristics, and we conduct an extensive experimental study comparing our methods with Tomita's baseline and with a state-of-the-art approach. Results show that two of our heuristics offer substantial efficiency improvements, especially on real-world graphs with social network properties.
format Preprint
id arxiv_https___arxiv_org_abs_2511_03525
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Engineering Algorithms for $\ell$-Isolated Maximal Clique Enumeration
D'Elia, Marco
Finocchi, Irene
Patrignani, Maurizio
Data Structures and Algorithms
G.2.2
Maximal cliques play a fundamental role in numerous application domains, where their enumeration can prove extremely useful. Yet their sheer number, even in sparse real-world graphs, can make them impractical to be exploited effectively. To address this issue, one approach is to enumerate $\ell$-isolated maximal cliques, whose vertices have (on average) less than $\ell$ edges toward the rest of the graph. By tuning parameter $\ell$, the degree of isolation can be controlled, and cliques that are overly connected to the outside are filtered out. Building on Tomita et al.'s very practical recursive algorithm for maximal clique enumeration, we propose four pruning heuristics, applicable individually or in combination, that discard recursive search branches that are guaranteed not to yield $\ell$-isolated maximal cliques. Besides proving correctness, we characterize both the pruning power and the computational cost of these heuristics, and we conduct an extensive experimental study comparing our methods with Tomita's baseline and with a state-of-the-art approach. Results show that two of our heuristics offer substantial efficiency improvements, especially on real-world graphs with social network properties.
title Engineering Algorithms for $\ell$-Isolated Maximal Clique Enumeration
topic Data Structures and Algorithms
G.2.2
url https://arxiv.org/abs/2511.03525