There are usually limited user evaluation of resources on a recommender system, which caused an extremely sparse user rating matrix, and this greatly reduce the accuracy of personalized recommendation, especially for new users or new items. This paper presents a recommendation method based on rating prediction using causal association rules.…

Included in this column are Star Trek, a geometric construction problem; a simplified approach to correlation using scattergrams; a calculus problem concerning second derivatives for extreme values; and a note on integration by parts. (MNS)