1. A method comprising, by one more computing systems: receiving an input from a user, wherein the input comprises free-form text; determining, through application of natural-language processing of the free-form text, one or more objects associated with the input; determining, through application of natural-language processing of the free-form text, one or more affinity declarations associated with the one or more objects; determining, from the one or more objects, an instance of a concept; determining an affinity coefficient between the user and the instance based on the affinity declaration; and storing the affinity coefficient in a data store in association with the user and the instance.