Learning users' interest categories is challenging in a dynamic environment
like the Web because they change over time, This article describes a novel
scheme to represent a user's interest categories, and an adaptive algorith
m to learn the dynamics of the user's interests through positive and negati
ve relevance feedback. We propose a three-descriptor model to represent a u
ser's interests, The proposed model maintains a long-term interest descript
or to capture the user's general interests and a short-term interest descri
ptor to keep track of the user's more recent, faster-changing interests. An
algorithm based on the three-descriptor representation is developed to acq
uire high accuracy of recognition for long-term interests, and to adapt qui
ckly to changing interests in the short-term, The model is also extended to
multiple three-descriptor representations to capture a broader range of in
terests. Empirical studies confirm the effectiveness of this scheme to accu
rately model a user's interests and to adapt appropriately to various level
s of changes in the user's interests.