A formal trust model based on recommendations

A modern society is based on the division of labor and people inevitably rely on others. Improvement in technology makes it possible to perform economical transactions between partners living in different geographical locations and who may never see each other during their life-span. Recommender systems guide people to buy goods materials based on information from other people. A large set of alternative ways to organize such systems exists. The information that other people provide may come from explicitly from ratings, tags, reviews, or implicitly from how they spend their time and money. The information obtained can be used to select, filter, or sort items. This thesis examines formal trust assessment models. Main contributions of the thesis can be summarized as following:? A formal model to assess the trust to the organizations in a specified contextset by using web-based survey data is developed. Addition of importance parameter to trust calculations and calculation of trust in real-numberintervals by selected confidence probability are the main contributions.? Trust and confidence propogation in trust chains are investigated. Propogation of confidence is here the main contribution.? Trust and confidence propogation in service oriented systems are modeled. Propogation of confidence in service-oriented systems is again the main contribution in this model.? A software tool called Trust Assesment Software Tool (TAST) has been developed. This is a flexible program that can be applied to the organizations working in the same business-field. TAST calculates the trust assessments of the organizations in selected time intervals. TAST can make trust assessment comparisons by competitor organizations in selected time intervals. ? We also show the applicability of our contributions by examples and case studies.vKeywords : trust, web, bi-partite graph, recommendation, trust metric, trust management, trust transitivity, web-based survey, trust chain.