which subclass of information filtering system was work of John Thomas Riedl
Recommender system A recommender system or a recommendation system (sometimes replacing "system" with a synonym such as platform or engine) is a subclass of information filtering system that seeks to predict the "rating" or "preference" that a user would give to an item.
Standard data system In work measurement, a standard data system is a database of normal time values, usually organized by work elements that can be used to establish time standards for tasks composed of work elements similar to those in the database.