Saturday, January 21, 2012

EPFL visit

I managed to make it to EPFL, Lausanne, a few months ago. EPFL has a great collection of researchers in communication/information theory, and it is always a pleasure to visit:
  • I discussed with Jean-Pierre Hubaux and Nevena Vratonjic about privacy and security in online advertising. They have a paper that studies the following question. ISPs can (a) cooperate with ad networks with direct traffic as usual, or (b) modify the traffic on the fly such that can divert part of the online advertising revenue for themselves. If this diversion becomes material, ad networks can secure the connection so ISPs can not divert the traffic. The paper studies the game theory between ISPs and ad networks and figures out the various equilibria.
  • I discussed the problem of identifying the same people/nodes/personas in two social networks, this is a popular problem to data mining community with no principled approach I know. Mathias (Matt) Grossglauser and Pedram Pedarsani take an interesting approach to this problem. Say there is an underlying network is an instance of G(n,p), the standard random graph. Consider G1 and G2, driving from the this instance by sampling each edge with prob s. Then, given only G1 and G2, can one retrieve the mapping of identical nodes? This is a coding theoretic way to approach the problem. The authors show that under certain conditions dependent on n,p and s, one can retrieve the entire mapping!
Matt, who has returned to EPFL after several years heading Nokia Research, was a great host and we were two geeks in the sauna, sweating, but still discussing puzzles. Over one dinner, I talked with Patrick Thiran and Martin Vetterli about compressed sensing and other problems. Over the other dinner, I discussed with the highly energetic Christoph Koch (who has meandered through research in logic to XML and databases) about theory and databases, and eventually debated the issue: does a research community like theory or databases tend to largely agree each year on how to rank the star candidates on the job market? And what does it mean, when the rank orders differ. I also had a great discussion with Katerina Argyraki about some streaming network measurement questions I should really think about. Some of the discussions veered to good natured debate whether international conferences had a strong US vs EU bias.
Lausanne has Art. One of my favorite ``museums'' in the world is collection de l'Art Brut at Lausanne, but I didnt get a chance to visit. Matt and I had a magic moment at Fondation de l'Hermitage when we stumbled onto a room full of crates marked Van Gogh, Bonnard, Vallotton etc. (obviously crates destined to deliver the masterpieces!). Finally, since the last time I was at Lausanne, the campus has a new building, the incredible, innovative Rolex Learning Center: a great fluid, undulating space that naturally finds sectional uses without explicit interior walls.