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: "a calculus of cyber physical systems"
  Abstract: We propose a hybrid process calculus for modelling and reasoning on cyber-physical systems (CPS{s}). The dynamics of the calculus is expressed in terms of a labelled transition system in the SOS style of Plotkin. This is used to define a bisimulation-based behavioural semantics which support compositional reasonings. Finally, we prove run-time properties and system equalities for a non-trivial case study.

Connected through hyperedge HE-1 (induced by source paper "hybrid rebeca modeling and analyzing of cyber physical systems"):
  with members:
    - "towards the modular specification and validation of cyber physical systems"
    - "a formal approach to cyber physical attacks"
    - "modelling and simulation of asynchronous real time systems using timed rebeca"

Connected through hyperedge HE-2 (induced by source paper "a probabilistic calculus of cyber physical systems"):
  with members:
    - "state of the art of cyber physical systems security an automatic control perspective"
    - "a formal approach to cyber physical attacks"
    - "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-3 (induced by source paper "a formal approach to cyber physical attacks"):
  with members:
    - "state of the art of cyber physical systems security an automatic control perspective"
    - "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-4 (induced by source paper "tracing where iot data are collected and aggregated"):
  with members:
    - "a step towards checking security in iot"

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.LO(Logic in Computer Science)