combination, similarity and neighborhood formation and component combination
in weighted hybrid systems. We also referred to some current software tools which
can be used to fit these functions to data (see also [29, 25]) when we are trying to
find weights, similarity or the parameters used that best model the dataset.
The research in aggregation functions is extensive with a number of important
results, some of which have been explored with the application to recommender
systems in mind. As only an introduction has been provided here, we recommend
the recent books listed under Further Reading which provide details of many aggregation methods.