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: "implementing rbac model in an operating system kernel"
  Abstract: In this paper, the implementation of an operating system oriented RBAC model is discussed. Firstly, on the basis of RBAC96 model, a new RBAC model named OSR is presented. Secondly, the OSR model is enforced in RFSOS kernel by the way of integrating GFAC method and Capability mechanism together. All parts of the OSR implementation are described in detail.

Connected through hyperedge HE-1 (induced by source paper "duplication of windows services"):
  with members:
    - "design and implementation of a network security management system"
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "suspicious taint based access control for protecting os from network attacks"
    - "compatible and usable mandatory access control for good enough os security"

Connected through hyperedge HE-2 (induced by source paper "design and implementation of a network security management system"):
  with members:
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "suspicious taint based access control for protecting os from network attacks"
    - "compatible and usable mandatory access control for good enough os security"

Connected through hyperedge HE-3 (induced by source paper "confining windows inter process communications for os level virtual machine"):
  with members:
    - "design and implementation of a network security management system"
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "suspicious taint based access control for protecting os from network attacks"

Connected through hyperedge HE-4 (induced by source paper "suspicious taint based access control for protecting os from network attacks"):
  with members:
    - "design and implementation of a network security management system"
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "compatible and usable mandatory access control for good enough os security"

Connected through hyperedge HE-5 (induced by source paper "virtualizing system and ordinary services in windows based os level virtual machines"):
  with members:
    - "design and implementation of a network security management system"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "suspicious taint based access control for protecting os from network attacks"

Connected through hyperedge HE-6 (induced by source paper "a study on altering postgresql from multi processes structure to multi threads structure"):
  with members:
    - "design and implementation of a network security management system"
    - "suspicious taint based access control for protecting os from network attacks"
    - "compatible and usable mandatory access control for good enough os security"

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.OS(Operating Systems)