Loop-erased partitioning of a graph: mean-field analysis

• Published in: Electronic journal of probability Vol. 27; no. none
• Main Authors: Avena, Luca, Gaudillière, Alexandre, Milanesi, Paolo, Quattropani, Matteo
• Format: Journal Article
• Language: English
• Published: Institute of Mathematical Statistics (IMS) 01.01.2022
• Subjects: Mathematics; Probability; 60J10; random partitions; 2010 Mathematics Subject Classification. 05C81; loop-erased random walk; 60J28 Discrete Laplacian; 05C85; spanning rooted forests; 60J27; Wilson's algorithm
• ISSN: 1083-6489; 1083-6489
• DOI: 10.1214/22-EJP792

We consider a random partition of the vertex set of an arbitrary graph that can be sampled using loop-erased random walks stopped at a random independent exponential time of parameter q > 0.The related random blocks tend to cluster nodes visited by the random walk-with generator the discrete Laplacianon time scale 1/q, with q being the tuning parameter. We explore the emerging macroscopic structure by analyzing 2-point correlations. To this aim, it is defined an interaction potential between pair of vertices, as the probability that they do not belong to the same block of the random partition. This interaction potential can be seen as an affinity measure for "densely connected nodes" and capture well-separated regions in network models presenting non-homogeneous landscapes. In this spirit, we compute this potential and its scaling limits on a complete graph and on a non-homogeneous weighted version with community structures. For the latter geometry we show a phase-transition for "community detectability" as a function of the tuning parameter and the edge weights.