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: "graph based preconditioning conjugate gradient algorithm for n 1 contingency analysis"
  Abstract: Contingency analysis (CA) plays a critical role to guarantee operation security in the modern power systems. With the high penetration of renewable energy, a real-time and comprehensive N-1 CA is needed as a power system analysis tool to ensure system security. In this paper, a graph-based preconditioning conjugate gradient (GPCG) approach is proposed for the nodal parallel computing in N-1 CA. To pursue a higher performance in the practical application, the coefficient matrix of the base case is used as the incomplete LU (ILU) preconditioner for each N-1 scenario. Additionally, the re-dispatch strategy is employed to handle the islanding issues in CA. Finally, computation performance of the proposed GPCG approach is tested on a real provincial system in China.

Connected through hyperedge HE-1 (induced by source paper "the ubiquity of large graphs and surprising challenges of graph processing extended survey"):
  with members:
    - "g core a core for future graph query languages"
    - "foundations of modern query languages for graph databases"
    - "the gremlin graph traversal machine and language invited talk"
    - "graphvista interactive exploration of large graphs"
    - "querying knowledge graphs by example entity tuples"
    - "standards for graph algorithm primitives"

Connected through hyperedge HE-2 (induced by source paper "graph computing based distributed fast decoupled power flow analysis"):
  with members:
    - "exploration of bi level pagerank algorithm for power flow analysis using graph database"
    - "cim e oriented graph database model architecture and parallel network topology processing"
    - "exploration of graph computing in power system state estimation"

Connected through hyperedge HE-3 (induced by source paper "graph computing based fast screening in contingency analysis"):
  with members:
    - "exploration of bi level pagerank algorithm for power flow analysis using graph database"
    - "cim e oriented graph database model architecture and parallel network topology processing"
    - "exploration of graph computing in power system state estimation"

Connected through hyperedge HE-4 (induced by source paper "a high performance energy management system based on evolving graph"):
  with members:
    - "cim e oriented graph database model architecture and parallel network topology processing"
    - "exploration of graph computing in power system state estimation"

Connected through hyperedge HE-5 (induced by source paper "substation one line diagram automatic generation and visualization"):
  with members:
    - "cim e oriented graph database model architecture and parallel network topology processing"
    - "exploration of graph computing in power system state estimation"

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)