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: "compatible and usable mandatory access control for good enough os security"
  Abstract: OS compromise is one of the most serious computer security problems today, but still not being resolved. Although people proposed different kinds of methods, they could not be accepted by most users who are non-expert due to the lack of compatibility and usability. In this paper, we introduce a kind of new mandatory access control model, named CUMAC, that aims to achieve good-enough security, high compatibility and usability. It has two novel features. One is access control based on tracing potential intrusion that can reduce false negatives and facilitate security configuration, in order to improve both compatibility and usability; the other is automatically figuring out all of the compatibility exceptions that usually incurs incompatible problems. The experiments performed on the prototype show that CUMAC can defense attacks from network, mobile disk and local untrustable users while keeping good compatibility and usability.

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"
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"

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"
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"

Connected through hyperedge HE-3 (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"
    - "implementing rbac model in an operating system kernel"

Connected through hyperedge HE-4 (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"
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"

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)