CSAIL Event Calendar

Search, Recommendations, and Spam

All modern search engines use the link structure of the web to rank web pages. Web spammers, a.k.a. search engine optimizers, use strategically placed additional links to enhance the ranks of the web pages of their customers. In the first part of the talk, I discuss how we can use geometric properties of the web graph to help identify spam. My main emphasis here will be on the so-called contribution set (a set from which a given page gets most of its rank) and a local algorithm to determine this contribution set. In the second part I will discuss recommendation systems which take into account trust relations expressed, e.g., in a social network. In order to select from the a priori infinite number of possible recommendations algorithms based on these trust networks, we formulate several natural axioms, and discuss what these axioms imply for the design of these recommendation systems.

The talk is based on joint work with R. Andersen, J. Chayes, U. Feige, A. Flaxman, J. Hopcroft, A. Kalai, V. Mirrokni, S-H. Teng and M.Tennenholtz.

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