To describe the concept of transitive trust in a simplified way, assume that agent A trusts agent B, and that agent B trusts agent C, then by transitivity, agent A trusts agent C. Trust transitivity manifests itself in various forms during real life human interaction, but can be challenging to concisely model in a formal way. In this paper we describe principles for expressing and analysing tra...

The explosive growth of the World Wide Web leads to the fast advancing development of e-commerce techniques. Recommender systems, which use personalised information filtering techniques to generate a set of items suitable to a given user, have received considerable attention. Userand item-based algorithms are two popular techniques for the design of recommender systems. These two algorithms are...

Trust and distrust are two increasingly important metrics in social networks. Since many of these networks are very large, it is only natural that not all users know each other. To this aim, propagation and aggregation operators are often used to estimate (dis)trust relations for users that are not directly connected through the network. In this paper, we introduce bilattice-based aggregation a...

E-mail services are essential in the Internet. However, the current e-mail architecture presents problems that open it to several threats. Alternatives have been proposed to solve some problems related to e-mail services, offering reliability and scalability to such systems. This work presents a distributed trust model, allowing to create dynamic and decentralized trusted server lists, through ...

Evolutionary game-theory is a powerful tool to investigate the development of complex relations between individuals such as the emergence of cooperation and trust. But the propagation of genes is an unrealistic assumption when it comes to model fast-changing social interactions. We show how a transition from evolutionary game-theory to learning can be made. Specifically, we show how cooperation...

The work discusses nonmonotonicity in terms of trust management systems and presents model allowing for credential revocation in the Rolebased Trust-management Framework. A freshness constraints have been adopted into RT Framework in order to overcome nonmonotonicity and turn it to be temporarily monotonic. The proposed model allows for freshness requirements specification on policy level and u...

The routing protocols in use today operate on implicit trust among the different routers. Specifically, the distance vector routing (DVR) protocols compute routing tables in a distributed manner, based on this implicit trust. This trust model however fails to ensure the factual correctness of the routing updates, which is very critical for secure routing. We propose a neighbor update propagatio...

The most recent invasions in social networks make it inevitable to develop a network with high dependence and confidence to users. Even though recommender systems of today use advanced parallelism in web development, achieving trustworthiness in such a system has been a challenging task for several years. To overcome the existing sparsity, scalability and dynamism in new item/user issues, we pr...

A novel social network based group decision making (SN-GDM) model with experts’ weights not provided beforehand and with the following four tuple information: trust; distrust; hesitancy; and inconsistency, is introduced. The concepts of trust score (TS) and knowledge degree (KD) are defined and combined into a trust order space. Then, a strict trust ranking order relation of trust function valu...