Regarding the analysis of Web communication, social and complex networks
the fast finding of most influential nodes in a network graph constitutes an
important research problem. We use two indices of the influence of those nodes,
namely, PageRank and a Max-linear model. We consider the PageRank as an autoregressive
process with a random number of random coefficients that depend on
ranks of incoming nodes and their out-degrees and assume that the coefficients are
independent and distributed with regularly varying tail and with the same tail index.
Then it is proved that the tail index and the extremal index are the same for both
PageRank and the Max-linear model and the values of these indices are found. The
achievements are based on the study of random sequences of a random length and
the comparison of the distribution of their maxima and linear combinations.