Hi

I am researching in the field of trust-aware collaborative filtering systems. I have developed a movie recommender system which is based on an implicit trust network. The implicit trust between two users is calculated based on their co-rated items. Recently, a reviewer has said that "social networks provide a lot of structural information. You only considered the adjacency, which is the most basic feature."

I want to know what are the other features of social network structure that can be taken into account? and how these features can be applied to a recommender system which works only based on rating data?

Thank you in advance.