Social Trust in a Familiar Community Eseosa Oshodin, Francisco Chiclana and Samad Ahmadi Abstract Most computation of social trust have been used for maintaining commu- nities of individuals, based on their past activities. The behaviour of idle individuals or non-contributors to the communities have been totally ignored in the computation as they might affect the representation of the trust computed for the individuals. If the trust for an individual have been misrepresented, other individuals in the com- munity will erroneously disengage or engage with the individual. In this paper, a new trust metric is proposed which is based on user’s pattern of interaction that will be able to assist other users in their decision making on whether to join or leave a community. Different trust features are analysed to evaluate trust values for each user, which is used to determine the trust communities of the users. 1 Introduction In the context of social network, people tend to have similar preferences with their trustworthy friends and also disclose their personal information to them. Accord- ing to Nepal [7], trust between people can be described as a “social element” for engagement, acceptance and other decisions. Trust is important to everyone’s daily life-activities. For example, before a person accepts the help of another person/group or a group decides to accept a person, they will require to know the trustworthiness of that person or group. This trustworthiness of people form familiar communities where their relationship can maintained and it can also be referred to for trust infor- mation, which can assist in decision making. Examples of the familiar communities exist in Facebook and twitter, where users become familiar after several interac- tions or engagements with themselves. But when trust information is unknown to a person, an inaccurate decision or no decision may be made by the person. Eseosa Oshodin, Francisco Chiclana and Samad Ahmadi De Montfort University, Leicester, e-mail: eseosa.oshodin, chiclana, sahmadi@dmu.ac.uk