1. A system comprising: a memory storing a graphical structure comprising a first node representing a person, and a second node representing a document in a document repository, the nodes being connected by an edge according to an automatically observed interaction between the person represented by the first node and the document represented by the second node, at least one of the nodes having a topic annotation denoting a topic, the interaction based at least in part on at least one of: a consumption activity by the person represented by the first node of the document represented by the second node, or a relationship between the person represented by the first node, and a second person represented by a third node; a node relatedness construct to calculate a distance between two nodes of the graphical structure; an input arranged to receive at least an identifier of a user who is represented by the first node; and an identifier/retriever arranged to identify one or more documents from the document repository by using the identifier and using the calculated distances between the two nodes.