Sparse random graphs with many triangles

Fuente: arXiv
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Auteurs principaux: Chakraborty, Suman, van der Hofstad, Remco, Hollander, Frank den
Format: Preprint
Publié: 2021
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author Chakraborty, Suman
van der Hofstad, Remco
Hollander, Frank den
author_facet Chakraborty, Suman
van der Hofstad, Remco
Hollander, Frank den
contents In this paper we consider the Erdős-Rényi random graph in the sparse regime in the limit as the number of vertices $n$ tends to infinity. We are interested in what this graph looks like when it contains many triangles, in two settings. First, we derive asymptotically sharp bounds on the probability that the graph contains a large number of triangles. We show that conditionally on this event, with high probability the graph contains an almost complete subgraph, i.e., the triangles form a near-clique, and has the same local limit as the original Erdős-Rényi random graph. Second, we derive asymptotically sharp bounds on the probability that the graph contains a large number of vertices that are part of a triangle. If order $n$ vertices are in triangles, then the local limit (provided it exists) is different from that of the Erdős-Rényi random graph. Our results shed light on the challenges that arise in the description of real-world networks, which often are sparse, yet highly clustered, and on exponential random graphs, which often are used to model such networks.
format Preprint
id arxiv_https___arxiv_org_abs_2112_06526
institution arXiv
publishDate 2021
record_format arxiv
spellingShingle Sparse random graphs with many triangles
Chakraborty, Suman
van der Hofstad, Remco
Hollander, Frank den
Probability
Combinatorics
05C80, 60F10
In this paper we consider the Erdős-Rényi random graph in the sparse regime in the limit as the number of vertices $n$ tends to infinity. We are interested in what this graph looks like when it contains many triangles, in two settings. First, we derive asymptotically sharp bounds on the probability that the graph contains a large number of triangles. We show that conditionally on this event, with high probability the graph contains an almost complete subgraph, i.e., the triangles form a near-clique, and has the same local limit as the original Erdős-Rényi random graph. Second, we derive asymptotically sharp bounds on the probability that the graph contains a large number of vertices that are part of a triangle. If order $n$ vertices are in triangles, then the local limit (provided it exists) is different from that of the Erdős-Rényi random graph. Our results shed light on the challenges that arise in the description of real-world networks, which often are sparse, yet highly clustered, and on exponential random graphs, which often are used to model such networks.
title Sparse random graphs with many triangles
topic Probability
Combinatorics
05C80, 60F10
url https://arxiv.org/abs/2112.06526