34 research outputs found

    A survey on compositional algorithms for verification and synthesis in supervisory control

    Get PDF
    This survey gives an overview of the current research on compositional algorithms for verification and synthesis of modular systems modelled as interacting finite-state machines. Compositional algorithms operate by repeatedly simplifying individual components of a large system, replacing them by smaller so-called abstractions, while preserving critical properties. In this way, the exponential growth of the state space can be limited, making it possible to analyse much bigger state spaces than possible by standard state space exploration. This paper gives an introduction to the principles underlying compositional methods, followed by a survey of algorithmic solutions from the recent literature that use compositional methods to analyse systems automatically. The focus is on applications in supervisory control of discrete event systems, particularly on methods that verify critical properties or synthesise controllable and nonblocking supervisors

    Itā€™s Not OK, Boomer: Preventing Financial Power-of-Attorney Abuse of Elders

    Get PDF

    Expressing Trouble in Conversation: An Interactional Challenge and an Achievement in Student Supervision

    Get PDF
    This thesis describes an understudied yet ubiquitous phenomenon in student supervision interaction: studentsā€™ expression of problems or concerns (ā€œtroubleā€ for short) in here-and-now supervision meetings. It can be a brief assessment like ā€œfirst term was not greatā€ or more complex descriptions of a problematic situation. The thesis investigates how students get to talk about the trouble and how supervisors respond to them. The study adopts conversation analysis to examine 94 cases of trouble reports and their responses from 12 hours of recorded real-time supervision meetings. It is found, across all kinds of supervision meetings, that students adopt two approaches to express trouble: direct trouble reports or ā€œtrouble projectionsā€ (utterances that project a trouble report). When students produce a trouble report without being solicited by supervisors, they establish the relevance of an incipient trouble report via embodied (e.g., face-touching, face tilting upwards, eye closing, and gaze aversion) and linguistic resources. When students have created the environment via these moves by students, trouble reports are produced as the claims of, e.g., negative emotions, difficulties and lack of knowledge. The thesis shows that trouble reports can be co-constructed by students and supervisors together to handle delicate matters. Students can start, but the supervisors collaboratively complete or produce the trouble reports in overlap when the trouble projectably involves critical elements toward the supervisor or the institution. Lastly, it is revealed that supervisors orient to advice-giving in response to trouble reports. Before the arrival of advice, supervisors frequently use other-initiated repair or follow-up questions to get to understand the trouble and to foreground the advice. Moreover, supervisors may respond with a comparable experience of their own to convey an empathetic stance. Alternatively, supervisors may offer ā€œunsupervisable responsesā€ in which they normalise the trouble as something that inevitably happens and thus is not advice relevant. Drawing on these findings, I argue that student trouble reports in supervision meetings are the product of emerging interaction, highly contingent on the elements of the sequential environment, the supervisorā€™s prior turns, and preference organisation. The thesis for the first time offers a systematic examination of student expression of trouble in supervision interaction. It reveals the embodied, linguistic, and sequential resources required for trouble reports. It also adds to the literature on the organisation of supervisory advice-giving

    Resonance, a step towards a fluency for complexity: The science, language, and epistemology of Gregory Bateson

    Get PDF
    This thesis confronts the urgency with which new language and vocabulary is required to move beyond linear assumptions in mainstream science and humanities, as well as global policy making. I examine Gregory Batesonā€™s body of work in history and philosophy of science, psychiatry and psychotherapy, anthropology, biology and ecology designed to communicate the necessarily interdisciplinary consideration for a nonlinear and recursive investigation of the self, other, and environment. Such intellectual forays cannot be dismissed as non-scientific. I offer definitions and contextualizations of key terms derived from cybernetics, new materialisms, and posthumanism (such as emergence, process, paradox, metaphor, fractality) to speak about the ramifying intricacies and pathologies in processes of knowing at various different scales. I conclude with a theory of resonance that may offer the epistemological groundwork with which to construct a metaphor of precarious intervention and to model a critical relationship between epistemology and ethics

    State v. Loya Respondent\u27s Brief Dckt. 44227

    Get PDF
    https://digitalcommons.law.uidaho.edu/not_reported/4368/thumbnail.jp

    Compositional supervisor synthesis with state merging and transition removal

    Get PDF
    This working paper proposes a framework to obtain memory-efficient supervisors for large discrete event systems, which are least restrictive, controllable, and nonblocking. The approach combines compositional synthesis and state-based abstraction with transition removal to mitigate the state-space explosion problem and reduce the memory requirements. Hiding and nondeterminism after abstraction are also supported. To ensure least restrictiveness after transition removal, the synthesised supervisor has the form of cascaded maps representing the safe states. These maps have lower space complexity than previous automata-based supervisors. The algorithm has been implemented in the DES software tool Supremica and applied to compute supervisors for several large industrial models. The results show that supervisor maps can be computed efficiently and in many cases require less memory than automata-based supervisors

    On Compositional Approaches for Discrete Event Systems Verification and Synthesis

    Get PDF
    Over the past decades, human dependability on technical devices has rapidly increased.Many activities of such devices can be described by sequences of events,where the occurrence of an event causes the system to go from one state to another.This is elegantly modelled by state machines. Systems that are modelledin this way are referred to as discrete event systems. Usually, these systems arehighly complex, and appear in settings that are safety critical, where small failuresmay result in huge financial and/or human losses. Having a control functionis one way to guarantee system correctness.The work presented in this thesis concerns verification and synthesis of suchsystems using the supervisory control theory proposed by Ramadge and Wonham. Supervisory control theory provides a general framework to automaticallycalculate control functions for discrete event systems. Given a model of thesystem, the plant to be controlled, and a specification of the desired behaviour,it is possible to automatically compute, i.e. synthesise, a supervisor that ensuresthat the specification is satisfied.Usually, systems are modular and consist of several components interactingwith each other. Calculating a supervisor for such a system in the straightforwardway involves constructing the complete model of the considered system, whichmay lead to the inherent complexity problem known as the state-space explosionproblem. This problem occurs as the number of states grows exponentially withthe number of components, which makes it intractable to examine the globalstates of a system due to lack of memory and time.One way to alleviate the state-space explosion problem is to use a compositionalapproach. A compositional approach exploits the modular structure of asystem to reduce the size of the model. This thesis mainly focuses on developingabstraction methods for the compositional approach in a way that the finalverification and synthesis results are the same as it would have been for the nonabstractedsystem. The algorithms have been implemented in the discrete eventsystem software tool Supremica and have been applied to verify and computememory efficient supervisors for several large industrial models

    On Compositional Approaches for Discrete Event Systems Verification and Synthesis

    Get PDF
    Over the past decades, human dependability on technical devices has rapidly increased.Many activities of such devices can be described by sequences of events,where the occurrence of an event causes the system to go from one state to another.This is elegantly modelled by state machines. Systems that are modelledin this way are referred to as discrete event systems. Usually, these systems arehighly complex, and appear in settings that are safety critical, where small failuresmay result in huge financial and/or human losses. Having a control functionis one way to guarantee system correctness.The work presented in this thesis concerns verification and synthesis of suchsystems using the supervisory control theory proposed by Ramadge and Wonham. Supervisory control theory provides a general framework to automaticallycalculate control functions for discrete event systems. Given a model of thesystem, the plant to be controlled, and a specification of the desired behaviour,it is possible to automatically compute, i.e. synthesise, a supervisor that ensuresthat the specification is satisfied.Usually, systems are modular and consist of several components interactingwith each other. Calculating a supervisor for such a system in the straightforwardway involves constructing the complete model of the considered system, whichmay lead to the inherent complexity problem known as the state-space explosionproblem. This problem occurs as the number of states grows exponentially withthe number of components, which makes it intractable to examine the globalstates of a system due to lack of memory and time.One way to alleviate the state-space explosion problem is to use a compositionalapproach. A compositional approach exploits the modular structure of asystem to reduce the size of the model. This thesis mainly focuses on developingabstraction methods for the compositional approach in a way that the finalverification and synthesis results are the same as it would have been for the nonabstractedsystem. The algorithms have been implemented in the discrete eventsystem software tool Supremica and have been applied to verify and computememory efficient supervisors for several large industrial models

    Certainly Unsupervisable States

    Get PDF
    This paper proposes an abstraction method for compositional synthesis. Synthesis is a method to automatically compute a control program or supervisor that restricts the behaviour of a given system to ensure safety and liveness. Compositional synthesis uses repeated abstraction and simplification to combat the state-space explosion problem for large systems. The abstraction method proposed in this paper finds and removes the so-called certainly unsupervisable states. By removing these states at an early stage, the final state space can be reduced substantially. The paper describes an algorithm with cubic time complexity to compute the largest possible set of removable states. A practical example demonstrates the feasibility of the method to solve real-world problems
    corecore