The proposed approach for decentralised social filtering consists of a c ontent-based filtering layer , a collaborative filtering layer and a social filtering layer on top of a multiagent system. However, it is possible to get a working system at each layer. The layers are shown in Figure 1. Figure 1 . The layers of the proposed system.
Happy faces symbolise the agents.
The second layer, the collaborative filtering layer , is based on the content-based filtering layer and its agents use of the content of documents to route and recommend interesting documents to each other and to its users. The third layer, the social filtering layer , is constructed on top of the collaborative filtering layer by computing a confidence value that states how much an agent trusts another agent for recommendations of interesting documents. Based on the trust, the agents can choose what other agents to subscribe recommendations from and what documents they should propose to the users. By using trust, an agent can propose documents based on a different criterion than the content similarity and because the trust is based on the users ratings, one can say that it is using a form of social filtering. In the proposed system, there are two types of agents, the Interface Agent and the Interest Agent.