Ilya’s slides are already on the web.

A few random notes:

• In 1994-1995 term frequency was state of the art in search engine relevancy.
• State of the art today = TF-IDF = Term Frequency – Inverse Document Frequency
• http://rubyforge.org/projects/gratr/ graph theory gem – gets slow after 1000 nodes but can manage about a million.
• Working with math in Ruby is not the best idea. Use GSL with one of the ruby binding gems.