1.3 Com paring collaborative and content-based methods 5 Multiagent Hy brid Recommendation 5.1 Introduction: Twothought systems 5.2 Design 5. 2.1 Selection agent adapt ation 5.2.2 Collection agent adapt ation 5.2.3 Profile splitting 5.2.4 Collection agent types 5.2.5 Including explicit collaboration 5.2.6 Advant ages of the ar chitecture 5. 2.7 Related work 5.3 Implement ation 100 5.3.1 Collection agent s 5.3.2 Central router 5.3.3 Selection agents 5.4 Experiment al metho dology 106 5.4.1 Profile accuracy 5.4.2 Comp ari son of sources 5.4.3 Declared topics 107 5.5 Experiment result s 5.5.1 Profile accuracy 108 5.5.2 omparison of sources 109 3.5. 3 Specializat 5.5.4 Seren dipity 5.5.5 User observations 112 5.6 Summary: Exploiting overl aps between interests4.3 Comparing collaborative and content-based methods ......... 77 5 Multiagent Hybrid Recommendation 81 5.1 Introduction: Two \thought systems" . . . . . . . . . . . . . . . . . . 83 5.2 Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 5.2.1 Selection agent adaptation . . . . . . . . . . . . . . . . . . . . 87 5.2.2 Collection agent adaptation ................... 88 5.2.3 Prole splitting . . . . . . . . . . . . . . . . . . . . . . . . . . 92 5.2.4 Collection agent types ...................... 94 5.2.5 Including explicit collaboration ................. 95 5.2.6 Advantages of the architecture . . . . . . . . . . . . . . . . . . 97 5.2.7 Related work ........................... 99 5.3 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100 5.3.1 Collection agents ......................... 101 5.3.2 Central router . . . . . . . . . . . . . . . . . . . . . . . . . . . 102 5.3.3 Selection agents . . . . . . . . . . . . . . . . . . . . . . . . . . 103 5.4 Experimental methodology . . . . . . . . . . . . . . . . . . . . . . . . 106 5.4.1 Prole accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . 106 5.4.2 Comparison of sources ...................... 107 5.4.3 Declared topics .......................... 107 5.5 Experiment results ............................ 108 5.5.1 Prole accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . 108 5.5.2 Comparison of sources ...................... 109 5.5.3 Specialization . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 5.5.4 Serendipity ............................ 111 5.5.5 User observations . . . . . . . . . . . . . . . . . . . . . . . . . 112 5.6 Summary: Exploiting overlaps between interests . . . . . . . . . . . . 113 xi