Recommender systems (Information filtering) Data mining 2 Data processing 2 Information filtering systems 2 Information retrieval 2 Machine learning 2 Cell phone systems 1 Computer programs 1 Correlation (Statistics) 1 Employees 1 Expert systems (Computer science) 1 Government policy 1 Human-computer interaction 1 Information services 1 Information storage and retrieval systems 1 Neural networks (Computer science) 1 Occupational training 1 Ontologies (Information retrieval) 1 Open source software 1 Quality control 1 Semantic Web 1 Tourism 1 Training of 1