Thesis subject:
Logic-based model of trust in composed services

Supervisors:
Guillaume Feuillade, Andreas Herzig
IRIT-LILaC, Toulouse, France

Description:
In some recent works (Lorini and Demolombe 2008, Lorini and Demolombe 2009, Herzig et al. 2010), in
the framework of the ANR ForTrust project (http://www.irit.fr/ForTrust, 2007-2010), a logical model
of trust has been devised. In this model the main constituents of trust conceived as a mental attitude
are formally characterized and its logical properties are studied. In accordance with the socio-cognitive
theory of trust proposed by (Castelfranchi and Falcone 1998, Falcone and Castelfranchi 2001), in the
ForTrust model, trust is defined as a belief of the truster about certain properties of the trustee 
which are relevant for the achievement of a goal of the truster. Among these properties, there are the
trustee's skills and abilities, and the trustee's willingness to perform a given action for the achievement
of the truster's goal. However, the ForTrust model is limited since it only considers an agent's 
trust in the atomic action of another agent and does not apply to trust in multi-agent plans where the
elements in the plan are atomic actions of different agents.

The aim of this research project is to extend the ForTrust logic-based model in order to obtain a new
logic-based model of trust which allows characterizing trust in multi-agent plans and, consequently,
trusting in composed e-services. 

In this new model, trust in a complex e-service will be defined in a compositional way from trust in
the components of that e-service. The model will also clarify the relationships between trust in complex
e-services and security properties like privacy, integrity and availability. For instance, the model 
will clarify the conditions under which an agent's belief about certain properties of the e-service 
related to security (e.g. whether the e-service preserves confidentiality and/or integrity of information)
supports the agent's trust in the complex e-service. The model will thus allow to express a composition
problem where a goal must be achieved using the available e-services under trust assumptions, the composition
problem translating into a satisfiability problem in the logic-based model of trust. This will allow 
extending existing service composition methods by adding the trust component in the equation.

The thesis is funded for 3 years by the ANR PIMI project (2010-2013) in which the LILaC group of IRIT takes
part and that is lead by e-Citiz.

Application:
Please send applications to feuillad@irit.fr and herzig@irit.fr.