A method and system of expertise discovery in social networks accesses behavioral information associated with users' use of a computer-implemented social network, whereby the computer-implemented social network enables its users to have subscribing relationships with other users. Expertise levels of users of the social network with respect to one or more topics are automatically inferred from the behavioral information. The behavioral information may comprise interactions by other users with respect to content published by a user. The expertise levels of users may be inferred in accordance with the expertise levels of other users who are subscribed to them. Recommendations of users based on their expertise levels may be delivered, as well as explanations for the recommendations. Expertise levels of multiple users and/or expertise levels of a user over time may be delivered for display.
Please help me write a proper abstract based on the patent claims. CLAIM: 1. A computer-implemented method, comprising: accessing automatically a plurality of usage behaviors associated with a plurality of users' use of a computer-implemented social network, wherein the computer-implemented social network comprises computer-implemented representations of a plurality of users of the computer-implemented social network and computer-implemented relationships among the plurality of users, wherein the computer-implemented relationships comprise subscribing relationships; inferring automatically an expertise level of a first user of the plurality of users with respect to one or more topics based upon a first plurality of the plurality of usage behaviors; generating automatically a recommendation comprising a representation of the first user for delivery to a second user of the computer-implemented social network, wherein the recommendation is generated in accordance with the inferred expertise level; and delivering the recommendation to the second user. 2. The method of claim 1, further comprising: inferring automatically the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors, wherein a plurality of the first plurality of usage behaviors comprise interactions of one or more of the plurality of users with respect to content authored by the first user. 3. The method of claim 1, further comprising: inferring automatically the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors and further based upon an automatic inference of an expertise level of a third user of the plurality of users, wherein one of the subscribing relationships is a subscribing relationship in which the third user subscribes to content published by the first user. 4. The method of claim 3, further comprising: inferring automatically the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors and further based upon the automatic inference of the expertise level of the third user of the plurality of users, wherein the inference of the expertise level of the third user is based upon a second plurality of the plurality of usage behaviors comprising interactions of one or more of the plurality of users with respect to content authored by the third user. 5. The method of claim 1, further comprising: inferring automatically the expertise level of the first user of the plurality of users with respect to the one or more topics, wherein the one or more topics are determined by the second user. 6. The method of claim 5, further comprising: inferring automatically the expertise level of the first user of the plurality of users with respect to the one or more topics, wherein the one or more topics are determined by the second user through application of a control that adjusts a topical neighborhood, wherein the topical neighborhood comprises a plurality of topics and weighted relationships among the plurality of topics. 7. The method of claim 1, further comprising: generating automatically the recommendation for delivery to the second user of the computer-implemented social network, wherein the recommendation is further generated in accordance with a degree of separation between the first user and the second user, wherein the degree of separation is determined from the computer-implemented relationships. 8. A computer-implemented system comprising one or more processor-based devices configured to: access a plurality of usage behaviors associated with a plurality of users' use of a computer-implemented social network, wherein the computer-implemented social network comprises computer-implemented representations of a plurality of users of the computer-implemented social network and computer-implemented relationships among the plurality of users, wherein the computer-implemented relationships comprise subscribing relationships; infer an expertise level of a first user of the plurality of users with respect to one or more topics based upon a first plurality of the plurality of usage behaviors; generate a recommendation comprising a representation of the first user for delivery to a second user of the computer-implemented social network, wherein the recommendation is generated in accordance with the inferred expertise level; and deliver the recommendation to the second user. 9. The system of claim 8, further comprising the one or more processor-based devices configured to: infer the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors, wherein a plurality of the first plurality of usage behaviors comprise interactions of one or more of the plurality of users with respect to content authored by the first user. 10. The system of claim 9, further comprising the one or more processor-based devices configured to: infer the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors, wherein the plurality of the first plurality of usage behaviors comprise interactions of the one or more of the plurality of users with respect to the content authored by the first user, wherein at least one of the interactions is a direct feedback behavior. 11. The system of claim 9, further comprising the one or more processor-based devices configured to: infer the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors and further based upon expertise calibration information. 12. The system of claim 11, further comprising the one or more processor-based devices configured to: infer the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors and further based upon the expertise calibration information, wherein the expertise calibration is determined from self-profiling content published by a user of the computer-implemented social network. 13. The system of claim 8, further comprising the one or more processor-based devices configured to: infer the expertise level of the first user of the plurality of users with respect to the one or more topics based upon the first plurality of the plurality of usage behaviors, wherein the one or more topics are determined from tags applied by users of the computer-implemented social network to content. 14. The system of claim 8, further comprising the one or more processor-based devices configured to: generate the recommendation, wherein the recommendation is further in accordance with one or more identified topics, wherein the one or more identified topics are identified based upon an item of content being accessed by the second user, wherein the item of content is related to at least one of the one or more identified topics being accessed by the second user. 15. The system of claim 8, further comprising the one or more processor-based devices configured to: generate an explanation for the recommendation, wherein the explanation comprises a reference to the expertise level; and deliver the explanation to the second user. 16. The system of claim 15, further comprising the one or more processor-based devices configured to: generate the explanation for the recommendation, wherein the explanation comprises the reference to the expertise level and further comprises a reference to a confidence level with respect to the recommendation. 17. A computer-implemented system comprising one or more processor-based devices configured to: access a plurality of usage behaviors associated with a plurality of users' use of a computer-implemented social network, wherein the computer-implemented social network comprises computer-implemented representations of a plurality of users of the computer-implemented social network and computer-implemented relationships among the plurality of users, wherein the computer-implemented relationships comprise subscribing relationships; infer a plurality of expertise levels, wherein each of the plurality of expertise levels is associated with a user of the plurality of users, wherein each of the plurality of expertise levels is with respect to one or more topics, and wherein each of the plurality of expertise levels is based upon a plurality of the plurality of usage behaviors; select, in accordance with a request from a first user of the social network, one or more of the plurality of expertise levels; and deliver for display the one or more expertise levels and a representation of the user associated with each of the one or more expertise levels. 18. The system of claim 17, further comprising the one or more processor-based devices configured to: infer the plurality of expertise levels, wherein each of the plurality of expertise levels is associated with the user of the plurality of users, wherein each of the plurality of expertise levels is based upon the plurality of the plurality of usage behaviors, and wherein the plurality of the plurality of usage behaviors comprise interactions of one or more of the plurality of users with respect to content authored by the user of the plurality of users who is associated with each expertise level. 19. The system of claim 17, further comprising the one or more processor-based devices configured to: select, in accordance with the request from the first user of the social network, the one or more of the plurality of expertise levels, wherein the request from the first user comprises the first user selecting one or more topics. 20. The system of claim 17, further comprising the one or more processor-based devices configured to: select, in accordance with the request from the first user of the social network, a plurality of expertise levels associated with a user of the social network, wherein the expertise levels correspond to different times.