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: "global grids and software toolkits a study of four grid middleware technologies"
  Abstract: Grid is an infrastructure that involves the integrated and collaborative use of computers, networks,#R##N#databases and scientific instruments owned and managed by multiple organizations. Grid applications often involve#R##N#large amounts of data and/or computing resources that require secure resource sharing across organizational#R##N#boundaries. This makes Grid application management and deployment a complex undertaking. Grid middlewares#R##N#provide users with seamless computing ability and uniform access to resources in the heterogeneous Grid#R##N#environment. Several software toolkits and systems have been developed, most of which are results of academic#R##N#research projects, all over the world. This chapter will focus on four of these middlewares—UNICORE, Globus,#R##N#Legion and Gridbus. It also presents our implementation of a resource broker for UNICORE as this functionality#R##N#was not supported in it. A comparison of these systems on the basis of the architecture, implementation model and#R##N#several other features is included.

Connected through hyperedge HE-1 (induced by source paper "on demand grid provisioning using cloud infrastructures and related virtualization tools a survey and taxonomy"):
  with members:
    - "market oriented cloud computing vision hype and reality for delivering it services as computing utilities"
    - "cloud computing and grid computing 360 degree compared"
    - "the anatomy of the grid enabling scalable virtual organizations"

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.DC(Distributed, Parallel, and Cluster Computing)