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: "archer a community distributed computing infrastructure for computer architecture research and education"
  Abstract: This paper introduces Archer, a community-based computing infrastructure supporting computer architecture research and education. The Archer system builds on virtualization techniques to provide a collaborative environment that facilitates sharing of computational resources and data among users. It integrates batch scheduling middleware to deliver high-throughput computing services aggregated from resources distributed across wide-area networks and owned by different participating entities in a seamless manner. The paper discusses the motivations that have led to the design of Archer, describes its core middleware components, and presents an analysis of the functionality and performance of the first wide-area deployment of Archer running a representative computer architecture simulation workload.

Connected through hyperedge HE-1 (induced by source paper "virtual private overlays secure group commounication in nat constrained environments"):
  with members:
    - "on the design and implementation of structured p2p vpns"
    - "a symphony conducted by brunet"
    - "peer to peer communication across network address translators"

Connected through hyperedge HE-2 (induced by source paper "on the design and implementation of structured p2p vpns"):
  with members:
    - "a symphony conducted by brunet"
    - "ip over p2p enabling self configuring virtual ip networks for grid computing"

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.AR(Hardware Architecture)