Reasoning about trust using argumentation: A position paper

2012

Previous work has used theories of evidence to incorporate belief into trust and reputation systems. Some important questions that remain, however, are how agents might recover reputation lost in disputed transactions, and how new agents with little or no past transaction history might enter the trust network. We attempt to address these issues by extending previous work using the Dempster-Shafer theory of evidence to include formal argumentation. Reasons for past bad transaction assignment can be taken into account in new transactions and discounted by importance. New agents can participate in trust networks by forwarding evidence as arguments in a distributed reputation system. We present our preliminary model on incorporation of argumentation frameworks into trust management systems to support more complex reasoning mechanisms.

2010

Trust in multiagent systems is used for seeking to minimize the uncertainty in the interactions among the agents. In this paper, we discuss how to use argumentation to reason about trust. Using the methodology of meta-argumentation, first we represent the source of the information from which the argument is constructed in the abstract argumentation framework capturing the fact that b is attacked because b is from a particular source s. We show how a source of information can be attacked if it is not evaluated as trustworthy. Second, we provide a fine grained representation of the trust relationships between the information sources in which trust concerns not only the sources but also the single arguments and attack relations the sources propose. Moreover, we represent the evidences in support of the arguments which are put forward by the information sources and the agents can express arguments by referring to other agents' arguments. Meta-argumentation allows us not to extend Dung's abstract argumentation framework by introducing trust and to reuse those principles and properties defined for Dung's framework.

2008

In an open Multi-Agent System, the goals of agents acting on behalf of their owners often conflict with each other. Therefore, a personal agent protecting the interest of a single user cannot always rely on them. Consequently, such a personal agent needs to be able to reason about trusting (information or services provided by) other agents. Existing algorithms that perform such reasoning mainly focus on the immediate utility of a trusting decision, but do not provide an explanation of their actions to the user.

2011

ABSTRACT In any group of agents, trust plays an important role. The degree to which agents trust one another will inform what they believe, and, as a result the reasoning that they perform and the conclusions that they come to when that involves information from other agents. In this paper we consider a group of agents with varying degrees of trust of each other, and examine the combinations of trust with the argumentation-based reasoning that they can carry out.

2008 Third International Conference on Dependability of Computer Systems DepCoS-RELCOMEX, 2008

Trustworthiness of IT systems can be justified using the concept of a trust case. A trust case is an argument structure which encompasses justification and evidence supporting claimed properties of a system. It represents explicitly an expert's way of assessing that a certain object has certain properties. Trust cases can be developed collaboratively on the basis of evidence and justification of varying quality. They can be complex structures impossible to comprehend fully by a non-expert. A postulated model of communicating trust case contents to an 'ordinary' user is an expert acting on user's behalf and communicating his/her assessment to the user. Therefore, a mechanism for issuing and aggregating experts' assessments is required. The paper proposes such a mechanism which enables assessors to appraise strength of arguments included in a trust case. The mechanism uses Dempster-Shafer's model of beliefs to deal with uncertainty resulting from the lack of knowledge of the expert. Different types of argumentation strategies were identified and for each of them appropriate combination rules were presented.

2004

The specification of argument-based negotiation in e-Commerce environments aims not only at the definition of the best dealing strategies to be used by any set of computational entities in such environments, but also to mimic in its minds the reasoning processes of their human peers. Reputation may be one important parameter to be taken into account in the process of trust evaluation in a negotiation, once it can be analyzed either in terms of the quality of knowledge it carries into the negotiation process, or the referentials it may impose. In this work, such a model will be materialized by a sound syntactic and semantic tool for logic-based argumentation, where entities called agents and multiagent systems set the computational methodology to be pursued in the process of problem solving.

The Knowledge Engineering Review, 2013

Agreement Technologies are needed for autonomous agents to come to mutually acceptable agreements, typically on behalf of humans. These technologies include trust computing, negotiation, argumentation and semantic alignment. In this paper, we identify a number of open questions regarding the integration of computational models and tools for trust computing with negotiation, argumentation and semantic alignment. We consider these questions in general and in the context of applications in open, distributed settings such as the grid and cloud computing.

2014

Trust and argumentation have both been the focus of much scholarly interest. While each topic has originated its own multidisciplinary literature (for an overview, see Castelfranchi & Falcone, 2010; van Eemeren et al., 2014), more recently they have started to be pursued in conjunction with each other. There are several reasons why looking at trust and argumentation together is considered especially fruitful. First, both phenomena share a common function: dealing with change and uncertainty in complex social environments. This is why they both constitute key pillars in the emerging and rapidly growing new field of agreement technologies (Ossowski, 2013). But their connections run deeper than that: on the one hand, the degree of (justified) trust we have in the source of an argument should affect how that argument is reconstructed and assessed (see for instance Paglieri et al., 2014); on the other hand, argumentation can be a powerful tool to reason about trust, making sure such trus...

Trust is a mechanism for managing the uncertainty about autonomous entities and the information they deal with. As a result, trust can play an important role in any decentralized system, and particularly in multiagent systems, where agents are often engage in competitive interactions. Following Castelfranchi and Falcone [1], we believe that trust is based on reasons.

Argument & Computation, 2014