Perhaps the link to the presentation wasn't too fortunate. The app store ranking algorithm is quite well known, and the presentation also includes information

Perhaps the link to the presentation wasn't too fortunate. The app store ranking algorithm is quite well known, and the presentation also includes information about it. In brief - first go the apps with search query in title/publisher name/in-app purchase names, then apps with search query in keywords. The sales are used as a tiebreaker. The problem is in the details & special cases. And that's what we more or less figured out :)