Risk Balance in Exchange Protocols

We study the behaviour of rational agents in exchange protocols which rely on trustees. We allow malicious parties to compromise the trustee by paying a cost and, thereby, present a game analysis that advocates exchange protocols which induce balanced risks on the participants. We also present a risk-balanced protocol for fair confidential secret comparison

Dynamic epistemic verification of security protocols: framework and case study

We propose a dynamic epistemic framework for the verification of security protocols. First, we introduce a dynamic epistemic logic equipped with iteration and cryptographic supplements in which we can formalize and check (epistemic) requirements of security protocols. On top of this, we give a general guide how to go from a protocol specification to its representation in our framework. We demonstrate this by checking requirements of a simplified version of a protocol for confidential message comparison

Logic of Information Flow on Communication Channels (Extended Abstract)

We develop an epistemic logic to specify and reason about information flow and its underlying communication channels. By combining ideas from Dynamic Epistemic Logic (DEL) and Interpreted Systems (IS), our semantics offers a natural and neat way of modelling multi-agent communication scenarios with different assumptions about the observational power of agents

Accuracy in Rating and Recommending Item Features

This paper discusses accuracy in processing ratings of and recommendations for item features. Such processing facilitates featurebased user navigation in recommender system interfaces. Item features, often in the form of tags, categories or meta-data, are becoming important hypertext components of recommender interfaces. Recommending features would help unfamiliar users navigate in such environments. This work explores techniques for improving feature recommendation accuracy. Conversely, it also examines possibilities for processing user ratings of features to improve recommendation of both features and items. This work’s illustrative implementation is a web portal for a museum collection that lets users browse, rate and receive recommendations for both artworks and interrelated topics about them. Accuracy measurements compare proposed techniques for processing feature ratings and recommending features. Resulting techniques recommend features with relative accuracy. Analysis indicates that processing ratings of either features or items does not improve accuracy of recommending the other

Refinement of Kripke Models for Dynamics

We propose a property-preserving refinement/abstraction theory for Kripke Modal Labelled Transition Systems incorporating not only state mapping but also label and proposition lumping, in order to have a compact but informative abstraction. We develop a 3-valued version of Public Announcement Logic (PAL) which has a dynamic operator that changes the model in the spirit of public broadcasting. We prove that the refinement relation on static models assures us to safely reason about any dynamic properties in terms of PAL-formulas on the abstraction of a model. The theory is in particular interesting and applicable for an epistemic setting as the example of the Muddy Children puzzle shows, especially in the view of the growing interest for epistemic modelling and (automatic) verification of communication protocols

Be Your Own Curator with the CHIP Tour Wizard [html]

Web 2.0 enables increased access to the museum digital collection. More and more, users will spend time preparing their visits to the museums and reflecting on them after the visits. In this context, the CHIP (Cultural Heritage Information Personalization) project offers tools to the users to be their own curator, e.g. planning a personalized museum tour, discovering interesting artworks they want to see in a 'virtual' or a 'real' tour and quickly finding their ways in the museum. In this paper we present the new additions to the CHIP tools, which target the above functionality - a Web-based Tour Preparation Wizard and an export of a personalized tour to an interactive Mobile Guide used in the physical museum space. In addition, the user interactions during a real museum visit are stored and synchronized with the user model, which is maintained at the museum Web site