  In this paper, we consider three variations on standard PageRank:
Non-backtracking PageRank, $\mu$-PageRank, and $\infty$-PageRank, all of which
alter the standard formula by adjusting the likelihood of backtracking in the
algorithm's random walk. We show that in the case of regular and bipartite
biregular graphs, standard PageRank and its variants are equivalent. We also
compare each centrality measure and investigate their clustering capabilities.
