Maximal Entropy Random Walk: solvable cases of dynamics

TL;DR

This paper analytically and numerically investigates the dynamics of maximal entropy random walk (MERW) and generic random walk (GRW) on Cayley trees and ladder graphs, revealing distinct static and dynamic behaviors, especially regarding relaxation times and trapping phenomena.

Contribution

It provides exact solutions for MERW on Cayley trees with various structures and explores the effects of defects on ladder graphs, highlighting new dynamical regimes and trapping effects.

Findings

MERW relaxation times scale differently depending on tree structure.

MERW exhibits exponential trapping in defective ladder regions.

GRW shows standard diffusive behavior regardless of defects.

Abstract

We focus on the study of dynamics of two kinds of random walk: generic random walk (GRW) and maximal entropy random walk (MERW) on two model networks: Cayley trees and ladder graphs. The stationary probability distribution for MERW is given by the squared components of the eigenvector associated with the largest eigenvalue \lambda_0 of the adjacency matrix of a graph, while the dynamics of the probability distribution approaching to the stationary state depends on the second largest eigenvalue \lambda_1. Firstly, we give analytic solutions for Cayley trees with arbitrary branching number, root degree, and number of generations. We determine three regimes of a tree structure that result in different statics and dynamics of MERW, which are due to strongly, critically, and weakly branched roots. We show how the relaxation times, generically shorter for MERW than for GRW, scale with the graph size. Secondly, we give numerical results for ladder graphs with symmetric defects. MERW shows a clear exponential growth of the relaxation time with the size of defective regions, which indicates trapping of a particle within highly entropic intact region and its escaping that resembles quantum tunneling through a potential barrier. GRW shows standard diffusive dependence irrespective of the defects.