This is intersting too bad the slides alone don't explain which algorithm/method are used to extract keywords and merge them. The ruby code is not self-explanat

This is intersting too bad the slides alone don't explain which algorithm/method are used to extract keywords and merge them. The ruby code is not self-explanatory to me. Luckily there is the video. Is it using machine learning, dynamic programming, semantic inference? Where is the Cypher? I'm watching the prez.