9. The method of claim 1 , further comprising: determining a measure of significance for the user for at least one of the topics at the upper topic level and for a subtopic of that topic, the subtopic being at the lower topic level.
9. The method of claim 1 , further comprising: determining a measure of significance for the user for at least one of the topics at the upper topic level and for a subtopic of that topic, the subtopic being at the lower topic level. 10. The method of claim 9 , wherein the measure of significance is determined for each topic in the topic set.