9. A system, comprising: a data store storing contextual profiles for resources, the contextual profiles specifying topic values that represent measures of relevance of the resources to each of a plurality of topics and a resource context system coupled to the data store, the resource context system including at least one processor configured to perform operations comprising: identifying, from the data store, a reference resource and a contextual profile for the reference resource; determining that relevance feedback data for the reference resource has at least a threshold level of similarity to the contextual profile for the reference resource, the determination being based on a difference between the relevance feedback data and topics specified by the contextual profile, the relevance feedback data specifying one or more topics that users have identified as relevant to the reference resource; in response to the determination, computing a first contextual profile for a different resource based on the contextual profile for the reference resource; and providing the first contextual profile to a processing system that is configured to identify the different resource as relevant to at least one topic from the first contextual profile when at least one topic value in the first contextual profile meets a topic value threshold for the at least one topic, wherein computing the first contextual profile comprises: representing the reference resource and the different resource as nodes in a weighted graph, the node for the different resource being connected to the reference resource by a weighted edge representing sequential selections of the different resource and the reference resource; and computing the first contextual profile based on a function of the weighted edge and the contextual profile for the reference resource.
9. A system, comprising: a data store storing contextual profiles for resources, the contextual profiles specifying topic values that represent measures of relevance of the resources to each of a plurality of topics and a resource context system coupled to the data store, the resource context system including at least one processor configured to perform operations comprising: identifying, from the data store, a reference resource and a contextual profile for the reference resource; determining that relevance feedback data for the reference resource has at least a threshold level of similarity to the contextual profile for the reference resource, the determination being based on a difference between the relevance feedback data and topics specified by the contextual profile, the relevance feedback data specifying one or more topics that users have identified as relevant to the reference resource; in response to the determination, computing a first contextual profile for a different resource based on the contextual profile for the reference resource; and providing the first contextual profile to a processing system that is configured to identify the different resource as relevant to at least one topic from the first contextual profile when at least one topic value in the first contextual profile meets a topic value threshold for the at least one topic, wherein computing the first contextual profile comprises: representing the reference resource and the different resource as nodes in a weighted graph, the node for the different resource being connected to the reference resource by a weighted edge representing sequential selections of the different resource and the reference resource; and computing the first contextual profile based on a function of the weighted edge and the contextual profile for the reference resource. 11. The system of claim 9 , wherein the resource context system is further configured to perform operations comprising: initializing topic values for the different resource to initial topic values; and computing the first contextual profile based on a function of the initial topic values and the contextual profile for the reference resource.