Seminar Details:

**LANS Informal Seminar***"A Dynamical System for PageRank with Time-Dependent Teleportation"*

DATE: May 13, 2013

TIME: 15:00:00 - 16:00:00

SPEAKER: David Gleich, *Assistant Professor, Purdue University *

LOCATION: Building 240, 1404-1405, Argonne National Laboratory

**Description:**

We propose a dynamical system that captures changes to the network centrality of nodes as external interest in those nodes vary. We derive this system by adding time-dependent teleportation to the PageRank score. The result is not a single set of importance scores, but rather a time-dependent set. These can be converted into ranked lists in a variety of ways, for instance, by taking the largest change in the importance score. For an interesting class of the dynamic teleportation functions, we derive closed form solutions for the dynamic PageRank vector. The magnitude of the deviation from a static PageRank vector is given by a PageRank problem with complex-valued teleportation parameters. Moreover, these dynamical systems are easy to evaluate. We demonstrate the utility of dynamic teleportation on both the article graph of Wikipedia, where the external interest information is given by the number of hourly visitors to each page, and the Twitter social network, where external interest is the number of tweets per month. For these problems, we show that using information from the dynamical system helps improve a prediction task and identify trends in the data. I'll also discuss some ideas on how this work may apply to graph analysis of the power grid.

Reference

[1] A Dynamical System for PageRank with Time-Dependent Teleportation http://arxiv.org/abs/1211.4266

Please send questions or suggestions to Debojyoti Ghosh: ghosh at mcs dot anl dot gov.