A Google patent was granted on October 20th, 2015 titled Producing a ranking for pages using distances in a Web-link graph. It presents some changes to Google’s original PageRank.
I wrote about the very first PageRank patent in my post The First PageRank Patent and the Newest, where I posted a link to the original provisional copy of Lawrence Page’s Improved Text Searching in Hypertext Systems (pdf – 1.7m)
Under this new patent, Google adds a diversified set of trusted pages to act as seed sites. When calculating rankings for pages. Google would calculate a distance from the seed pages to the pages being ranked. A use of a trusted set of seed sites may sound a little like the TrustRank approach developed by Stanford and Yahoo a few years ago as described in Combating Web Spam with TrustRank (pdf). I don’t know what role, if any, the Yahoo paper had on the development of the approach in this patent application, but there seems to be some similarities.