Context-dependent Trust Decisions with Subjective Logic

A decision procedure implemented over a computational trust mechanism aims to allow for decisions to be made regarding whether some entity or information should be trusted. As recognised in the literature, trust is contextual, and we describe how such a context often translates into a confidence level which should be used to modify an underlying trust value. J{\o}sang's Subjective Logic has long been used in the trust domain, and we show that its operators are insufficient to address this problem. We therefore provide a decision-making approach about trust which also considers the notion of confidence (based on context) through the introduction of a new operator. In particular, we introduce general requirements that must be respected when combining trustworthiness and confidence degree, and demonstrate the soundness of our new operator with respect to these properties.Comment: 19 pages, 4 figures, technical report of the University of Aberdeen (preprint version

Panini: a concurrent programming model for solving pervasive and oblivious interference

Modular reasoning about concurrent programs is complicated by the possibility of interferences happening between any two instructions of a task (pervasive interference), and these interferences not giving out any information about the behaviors of potentially interfering concurrent tasks (oblivious interference). Reasoning about a concurrent program would be easier if a programmer modularly and statically (1) knows precisely the program points at which interferences may happen (sparse interference), and (2) has some insights into behaviors of potentially interfering tasks at these points (cognizant interference). In this work we present Panini, a core concurrent calculus which guarantees sparse interference, by controlling sharing among concurrent tasks, and cognizant interference, by controlling dynamic name bindings and accessibility of states of tasks. Panini promotes capsule-oriented programming whose concurrently running capsules own their states, communicate by asynchronous invocations of their procedures and dynamically transfer ownership. Panini limits sharing among two capsules to other capsules and futures, limits accessibility of a capsule states to only through its procedures and dispatches a procedure invocation on the static type of its receiver capsule. We formalize Panini, present its semantics and illustrate how its interference model, using behavioral contracts, enables Hoare-style modular reasoning about concurrent programs with interference

Public ubiquitous computing systems:lessons from the e-campus display deployments

In this paper we reflect on our experiences of deploying ubiquitous computing systems in public spaces and present a series of lessons that we feel will be of benefit to researchers planning similar public deployments. We focus on experiences gained from building and deploying three experimental public display systems as part of the e-campus pro ject. However, we believe the lessons are likely to be generally applicable to many different types of public ubicomp deployment

08241 Abstracts Collection -- Transactional Memory : From Implementation to Application

From 08.06. to 13.06.2008, the Dagstuhl Seminar 08241 ``Transactional Memory: From Implementation to Application\u27\u27 was held in Schloss Dagstuhl -- Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

04441 Abstracts Collection -- Mobile Information Management

From 24.10.04 to 29.10.04, the Dagstuhl Seminar 04441 ``Mobile Information Management\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available

Is my configuration any good: checking usability in an interactive sensor-based activity monitor

We investigate formal analysis of two aspects of usability in a deployed interactive, configurable and context-aware system: an event-driven, sensor-based homecare activity monitor system. The system was not designed from formal requirements or specification: we model the system as it is in the context of an agile development process. Our aim was to determine if formal modelling and analysis can contribute to improving usability, and if so, which style of modelling is most suitable. The purpose of the analysis is to inform configurers about how to interact with the system, so the system is more usable for participants, and to guide future developments. We consider redundancies in configuration rules defined by carers and participants and the interaction modality of the output messages.Two approaches to modelling are considered: a deep embedding in which devices, sensors and rules are represented explicitly by data structures in the modelling language and non-determinism is employed to model all possible device and sensor states, and a shallow embedding in which the rules and device and sensor states are represented directly in propositional logic. The former requires a conventional machine and a model-checker for analysis, whereas the latter is implemented using a SAT solver directly on the activity monitor hardware. We draw conclusions about the role of formal models and reasoning in deployed systems and the need for clear semantics and ontologies for interaction modalities