• Conference Object  

      Approximating optimal place sensor selection for structural observability in discrete event systems modeled by petri nets 

      Ru, Y.; Hadjicostis, Christoforos N. (2007)
      In this paper, we study place sensor selection problems in Discrete Event Systems modeled by Petri nets with outputs (i.e., Petri nets with transition and place sensors). Our goal is to place a minimal number of sensors ...
    • Conference Object  

      Constrained sensor selection for discrete event systems modeled by Petri nets 

      Ru, Y.; Hadjicostis, Christoforos N. (2011)
      This paper studies how to place a minimum number of sensors in discrete event systems modeled by partially observed Petri nets while maintaining structural observability. When the sensors are constrained to be associated ...
    • Article  

      Coverage analysis of mobile agent trajectory via state-based opacity formulations 

      Saboori, A.; Hadjicostis, Christoforos N. (2011)
      This paper performs coverage analysis of mobile agent trajectory utilizing discrete event system models and employing state-based notions of opacity. Non-deterministic finite automata with partial observation on their ...
    • Article  

      Current-state opacity formulations in probabilistic finite automata 

      Saboori, A.; Hadjicostis, Christoforos N. (2014)
      A system is said to be current-state opaque if the entrance of the system state to a set of secret states remains opaque (uncertain) to an intruder - at least until the system leaves the set of secret states. This notion ...
    • Conference Object  

      Decentralized failure diagnosis in discrete event systems 

      Athanasopoulou, E.; Hadjicostis, Christoforos N. (2006)
      In this paper, we develop and analyze decentralized failure diagnosis schemes for systems that can be modeled as finite state machines (FSMs). We consider a scenario where we are given multiple local diagnosers (with partial ...
    • Conference Object  

      Decentralized state estimation in discrete event systems under partially ordered observation sequences 

      Hadjicostis, Christoforos N.; Seatzu, C. (Institute of Electrical and Electronics Engineers Inc., 2016)
      We consider the problem of decentralized state estimation, where two or more observation sites send information to a coordinator who aims to determine the set of possible current states of a given discrete event system ...
    • Conference Object  

      Detectability in stochastic discrete event systems 

      Keroglou, C.; Hadjicostis, Christoforos N. (IFAC Secretariat, 2014)
      In this paper we define and analyze notions of detectability in stochastic discrete event systems (SDES). More specifically, we introduce the notions of A-detectability and AA-detectability which focus on characterizing ...
    • Article  

      Detectability in stochastic discrete event systems 

      Keroglou, C.; Hadjicostis, Christoforos N. (2015)
      A discrete event system possesses the property of detectability if it allows an observer to perfectly estimate the current state of the system after a finite number of observed symbols, i.e., detectability captures the ...
    • Conference Object  

      Development of a discrete event dynamic systems curriculum using a Web-based "real-time" simulated factory 

      Cassandras, C. G.; Deng, M.; Hu, J. Q.; Vakili, P.; Zhao, C.; Panayiotou, Christos G. (IEEE, 2004)
      Summary form only given. This paper aims at an integrative and innovative approach to curriculum methods of teaching engineering methodology courses. The course is problem driven where industrial case studies are the basis ...
    • Conference Object  

      Distributed diagnosis using predetermined synchronization strategies in the presence of communication constraints 

      Keroglou, C.; Hadjicostis, Christoforos N. (IEEE Computer Society, 2015)
      We consider distributed fault diagnosis in a discrete event system modeled as a nondeterministic finite automaton that is observed at multiple observation sites through distinct natural projection maps. The majority of ...
    • Article  

      Distributed Fault Diagnosis in Discrete Event Systems via Set Intersection Refinements 

      Keroglou, C.; Hadjicostis, Christoforos N. (2018)
      We extend and verify diagnosability for a class of set intersection refinement strategies, which can be used for distributed state estimation and fault diagnosis in nondeterministic finite automata that are observed at ...
    • Article  

      Fault model identification and synthesis in Petri nets 

      Cabasino, M. P.; Giua, A.; Hadjicostis, Christoforos N.; Seatzu, C. (2015)
      Fault identification studies in the Discrete Event Systems literature are typically model-based and require knowledge of the structure of the system, including the nature (and behavior) of the possible faults. In this paper ...
    • Conference Object  

      Hidden markov model classification based on empirical frequencies of observed symbols 

      Keroglou, C.; Hadjicostis, Christoforos N. (IFAC Secretariat, 2014)
      Given a sequence of observations, classification among two known hidden Markov models (HMMs) can be accomplished with a classifier that minimizes the probability of error (i.e., the probability of misclassification) by ...
    • Article  

      Marking observer in labeled petri nets with application to supervisory control 

      Cabasino, M. P.; Hadjicostis, Christoforos N.; Seatzu, C. (2017)
      In this paper, we consider the problem of marking estimation in labeled Petri nets whose initial marking is known to belong to a given convex set, in the presence of silent transitions (i.e., transitions labeled with the ...
    • Conference Object  

      Marking observer of labeled petri nets with uncertainty in the initial marking 

      Cabasino, M. P.; Seatzu, C.; Hadjicostis, Christoforos N. (2013)
      In this paper we consider marking estimation in labeled Petri nets whose initial marking is known to belong to a given convex set. We allow for silent transitions (i.e., transitions labeled with the empty word) and ...
    • Article  

      Monitoring discrete event systems using Petri net embeddings 

      Hadjicostis, Christoforos N.; Verghese, G. C. (1999)
      In this paper we discuss a methodology for monitoring failures and other activity in discrete event systems that are described by Petri nets. Our method is based on embedding the given Petri net model in a larger Petri net ...
    • Conference Object  

      Notions of security and opacity in discrete event systems 

      Saboori, A.; Hadjicostis, Christoforos N. (2007)
      In this paper, we follow a state-based approach to extend the notion of opacity in computer security to discrete event systems. A system is (S, P)-opaque if the evolution of its true state through a set of secret states S ...
    • Article  

      On the history of diagnosability and opacity in discrete event systems 

      Lafortune, S.; Lin, F.; Hadjicostis, Christoforos N. (2018)
      This paper presents historical remarks on key projects and papers that led to the development of a theory of event diagnosis for discrete event systems modeled by finite-state automata or Petri nets in the 1990s. The goal ...
    • Conference Object  

      Opacity formulations and verification in discrete event systems 

      Hadjicostis, Christoforos N.; Keroglou, C. (Institute of Electrical and Electronics Engineers Inc., 2014)
      In many emerging security applications, a property of a system, that may reveal important details about its behaviour, needs to be kept secret (opaque) to outside observers (intruders). Motivated by such applications, ...
    • Article  

      Opacity-enforcing supervisory strategies via state estimator constructions 

      Saboori, A.; Hadjicostis, Christoforos N. (2012)
      State-based notions of opacity, such as initial-state opacity and infinite-step opacity, emerge as key properties in numerous security applications of discrete event systems. We consider systems that are modeled as partially ...