Verifying one hundred prisoners and a lightbulb

This is a case-study in knowledge representation and dynamic epistemic protocol verification. We analyze the `one hundred prisoners and a lightbulb' puzzle. In this puzzle it is relevant what the agents (prisoners) {\em know}, how their knowledge {\em changes} due to {\em observations}, and how they affect the state of the world by {\em changing facts}, i.e., by their actions. These actions depend on the history of previous actions and observations. Part of its interest is that all actions are {\em local}, i.e.\ not publicly observable, and part of the problem is therefore how to disseminate local results to other agents, and make them {\em global}. The various solutions to the puzzle are presented as protocols (iterated functions from agent's local states, and histories of actions, to actions

Hidden protocols: Modifying our expectations in an evolving world

When agents know a protocol, this leads them to have expectations about future observations. Agents can update their knowledge by matching their actual observations with the expected ones. They eliminate states where they do not match. In this paper, we study how agents perceive protocols that are not commonly known, and propose a semantics-driven logical framework to reason about knowledge in such scenarios. In particular, we introduce the notion of epistemic expectation models and a propositional dynamic logic-style epistemic logic for reasoning about knowledge via matching agentsÊ expectations to their observations. It is shown how epistemic expectation models can be obtained from epistemic protocols. Furthermore, a characterization is presented of the effective equivalence of epistemic protocols. We introduce a new logic that incorporates updates of protocols and that can model reasoning about knowledge and observations. Finally, the framework is extended to incorporate fact-changing actions, and a worked-out example is given. © 2013 Elsevier B.V

MCMAS: an open-source model checker for the verification of multi-agent systems

We present MCMAS, a model checker for the verification of multi-agent systems. MCMAS supports efficient symbolic techniques for the verification of multi-agent systems against specifications representing temporal, epistemic and strategic properties. We present the underlying semantics of the specification language supported and the algorithms implemented in MCMAS, including its fairness and counterexample generation features. We provide a detailed description of the implementation. We illustrate its use by discussing a number of examples and evaluate its performance by comparing it against other model checkers for multi-agent systems on a common case study

Comparing approaches for model-checking strategies under imperfect information and fairness constraints

Starting from Alternating-time Temporal Logic, many logics for reasoning about strategies in a system of agents have been proposed. Some of them consider the strategies that agents can play when they have partial information about the state of the system. ATLKirF is such a logic to reason about uniform strategies under unconditional fairness constraints. While this kind of logics has been extensively studied, practical approaches for solving their model- checking problem appeared only recently. This paper considers three approaches for model checking strategies under partial observability of the agents, applied to ATLKirF . These three approaches have been implemented in PyNuSMV, a Python library based on the state-of- the-art model checker NuSMV. Thanks to the experimental results obtained with this library and thanks to the comparison of the relative performance of the approaches, this paper provides indications and guidelines for the use of these verification techniques, showing that different approaches are needed in different situations

MCMAS: an open-source model checker for the verification of multi-agent systems

We present MCMAS, a model checker for the verification of multi-agent systems. MCMAS supports efficient symbolic techniques for the verification of multi-agent systems against specifications representing temporal, epistemic and strategic properties. We present the underlying semantics of the specification language supported and the algorithms implemented in MCMAS, including its fairness and counterexample generation features. We provide a detailed description of the implementation. We illustrate its use by discussing a number of examples and evaluate its performance by comparing it against other model checkers for multi-agent systems on a common case study

systems

Verification of partial-information probabilisti

Comparing approaches for model-checking strategies under imperfect information and fairness constraints

Starting from Alternating-time Temporal Logic, many logics for reasoning about strategies in a system of agents have been proposed. Some of them consider the strategies that agents can play when they have partial information about the state of the system. ATLKirF is such a logic to reason about uniform strategies under unconditional fairness constraints. While this kind of logics has been extensively studied, practical approaches for solving their model- checking problem appeared only recently. This paper considers three approaches for model checking strategies under partial observability of the agents, applied to ATLKirF . These three approaches have been implemented in PyNuSMV, a Python library based on the state-of- the-art model checker NuSMV. Thanks to the experimental results obtained with this library and thanks to the comparison of the relative performance of the approaches, this paper provides indications and guidelines for the use of these verification techniques, showing that different approaches are needed in different situations

Faith, Hope, and Torture: Music in the Prisoner-of-War Camps of North Vietnam

North Vietnams cruel treatment of captured American pilots included music torture which rivaled the CIAs program in Guantnamo Bay, but the aural persecution suffered for nearly a decade by the American prisoners of war has never been documented. Unlike other victims of music torture, the prisoners consistently turned to music as a healing, empowering, and unifying force, which raises several questions. Why did the POWs fare better than Guantnamo detainees? Can music reverse the trauma that music torture caused? How do we determine which music will cause harm and which music will heal? Through numerous interviews with repatriated POWs and extensive research of memoirs, biographies, and military sources, I evaluate the damage caused by musical torture, the effectiveness of musical propaganda, and the ability of music to counteract the damage it caused. First, I show how faith (in God, country, family, and other prisoners) was key to survival, inspiring POWs to risk punishment and death for the chance to express their faith musically. Next, I demonstrate their incredible methods of creating, performing, and teaching music in hostile environments to keep hope alive. Finally, I examine the torture techniques utilized by the North Vietnamese, analyzing their music torture and propaganda programs to determine why their attempts at brainwashing failed and why the POWs suffered no long-term effects.While certain music caused harm, most POWs thought music helped them survive. Music was essential for their mental health and unity, providing an outlet for frustration, a method of communication, and hope for the future. By reclaiming music for their own purposes, the POWs overcame the trauma of music torture

Bereavement experiences of male prisoners : grief, cumulative loss and imprisonment

The central aim of this research was to explore and understand the grief experience of male prisoners as it occurs, and the impact of cumulative loss caused by death, prior to custodial sentencing. The responses of other inmates and the ways in which staff facilitated and managed prisoners’ grief were also the focus of enquiry.The research methods used were participant observation and semi-structured interviewing. Twenty-three bereaved prisoners participated. Also involved were 23 members of staff of different occupations and grades, and three volunteers. All participants were residing or working within a male, Category C prison in the north of England.Findings demonstrated that grief could not easily be confronted and processed as a result of: the many restraints imposed institutionally, the hegemonic culture, lack of trust and high levels of felt frustration due to constricted agency. Avoidant coping strategies were common, alongside an unwillingness to reach out for support. The evidence strongly suggests that prisoners can be at heightened risk of a more complex grief reaction than the normal population.This study provides a major contribution to both the criminological and thanatological fields. It makes policy and other recommendations, and widens the current international debate by offering a critique of the proposed Persistent Complex Bereavement Disorder (APA, 2013). The narrative accounts have produced evidence of negative and positive stressors uniquely found within the prison setting, demonstrating in a new way how they can impact upon the grieving process, using Stroebe and Schut’s (1999, 2016) Dual Process Model. Recognising excessive grief reactions, a theory is proposed – ‘Prisoners’ Grief Overload theory.’ Finally, a proposition is put forward for future inquiry: a significant bereavement can become a factor in putative desistance from crime if grief stressors are adequately confronted and processed, and a new individualised truth is attained