human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "state of the art of cyber physical systems security an automatic control perspective"
  Abstract: Cyber-physical systems are integrations of computation, networking, and physical processes. Due to the tight cyber-physical coupling and to the potentially disrupting consequences of failures, security here is one of the primary concerns. Our systematic mapping study sheds light on how security is actually addressed when dealing with cyber-physical systems from an automatic control perspective. The provided map of 138 selected studies is defined empirically and is based on, for instance, application fields, various system components, related algorithms and models, attacks characteristics and defense strategies. It presents a powerful comparison framework for existing and future research on this hot topic, important for both industry and academia.

Connected through hyperedge HE-1 (induced by source paper "actuator security indices based on perfect undetectability computation robustness and sensor placement"):
  with members:
    - "a security index for actuators based on perfect undetectability properties and approximation"
    - "controllability metrics limitations and algorithms for complex networks"
    - "computing critical k tuples in power networks"
    - "learning with submodular functions a convex optimization perspective"

Connected through hyperedge HE-2 (induced by source paper "security attacks on smart grid scheduling and their defences a game theoretic approach"):
  with members:
    - "real time detection of hybrid and stealthy cyber attacks in smart grid"
    - "a dynamic game approach for demand side management scheduling energy storage with forecasting errors"

Connected through hyperedge HE-3 (induced by source paper "security for cyber physical systems leveraging cellular networks and fog computing"):
  with members:
    - "mobile edge computing fog et al a survey and analysis of security threats and challenges"

Connected through hyperedge HE-4 (induced by source paper "a probabilistic calculus of cyber physical systems"):
  with members:
    - "a formal approach to cyber physical attacks"
    - "a calculus of cyber physical systems"
    - "compositional bisimulation metric reasoning with probabilistic process calculi"
    - "modelling mac layer communications in wireless systems"
    - "revisiting trace and testing equivalences for nondeterministic and probabilistic processes"

Connected through hyperedge HE-5 (induced by source paper "a formal approach to cyber physical attacks"):
  with members:
    - "a calculus of cyber physical systems"
    - "towards the automated verification of cyber physical security protocols bounding the number of timed intruders"
    - "cpdy extending the dolev yao attacker with physical layer interactions"

Connected through hyperedge HE-6 (induced by source paper "a calculus of cyber physical systems"):
  with members:
    - "a formal approach to cyber physical attacks"
    - "modelling mac layer communications in wireless systems"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.SY(Systems and Control)