Assortment of Other Speciﬁc Graph Traversal Use Cases
• Missing friends: Find all the friends of person A. Then ﬁnd all the
friends of the friends of person A that are not also person A’s friends.19
• Collaborative ﬁltering: Find all the items that the person A likes. Then
ﬁnd all the people that like those same items. Then ﬁnd which items
those people like that are not already the items that are liked by person
This algorithm is based on the notion of trying to close “open triangles” in the friendship graph. If
many of person A’s friends are friends with person B , then its likely that A and B know each other.
This is the most concise representation of collaborative ﬁltering. There are numerous modiﬁcations to
this general theme that can be taken advantage of to alter the recommendations.