Jiefei Ma

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Despite several research studies, the effective analysis of policy based systems remains a significant challenge. Policy analysis should at least (<i>i</i>) be expressive (<i>ii</i>) take account of obligations and authorizations, (<i>iii</i>) include a dynamic system model, and (<i>iv</i>) give useful diagnostic information. We present a logic-based policy(More)
Access control operates under the assumption that it is possible to correctly encode and predict all subjects' needs and rights. However, in human-centric pervasive domains, such as health care, it is hard if not impossible to encode all emergencies and exceptions, but also to imagine a priori all the permissible requests. Break-glass is an approach that(More)
Abductive reasoning is a well established field of Artificial Intelligence widely applied to different problem domains not least cognitive robotics and planning. It has been used to ab-duce high-level descriptions of the world from robot sense data, using rules that tell us what sense data would be generated by certain objects and events of the robots(More)
Pandora is a tool for supporting the learning of first order natural deduction. It includes a help window, an interactive context sensitive tutorial known as the " e-tutor " and facilities to save, reload and export to latex. Every attempt to apply a natural deduction rule is met with either success or a helpful error message, providing the student with(More)
We present a generalisation of the Event Calculus, specified in classical logic and implemented in ASP, that facilitates reasoning about non-binary-valued fluents in domains with non-deterministic, triggered, concurrent, and possibly conflicting actions. We show via a case study how this framework may be used as a basis for a " possible-worlds " style(More)
Answer sharing is a key element in multi-agent systems as it allows agents to collaborate towards achieving a global goal. However exogenous knowledge of the world can influence each agent's local computation, and communication channels may introduce delays, creating multiple partial answers at different times. Agent's answers may, therefore, be incomplete(More)
Short term studies in controlled environments have shown that user behaviour is consistent enough to predict disruptive smartphone notifications. However, in practice, user behaviour changes over time (concept drift) and individual user preferences need to be considered. There is a lack of research on which methods are best suited for predicting disruptive(More)
Abductive inference has many known applications in multi-agent systems. However, most abductive frameworks rely on a centrally executed proof procedure whereas many of the application problems are distributed by nature. Confidentiality and communication overhead concerns often preclude transmitting all the knowledge required for centralised reasoning. We(More)