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: "incremental maintenance for leapfrog triejoin"
  Abstract: We present an incremental maintenance algorithm for leapfrog triejoin. The algorithm maintains rules in time proportional (modulo log factors) to the edit distance between leapfrog triejoin traces.

Connected through hyperedge HE-1 (induced by source paper "distributed evaluation of subgraph queries using worstcase optimal lowmemory dataflows"):
  with members:
    - "size bounds and query plans for relational joins"
    - "worst case optimal algorithms for parallel query processing"
    - "skew strikes back new developments in the theory of join algorithms"
    - "communication steps for parallel query processing"
    - "tri tri again finding triangles and small subgraphs in a distributed setting"
    - "leapfrog triejoin a worst case optimal join algorithm"
    - "dbtoaster higher order delta processing for dynamic frequently fresh views"

Connected through hyperedge HE-2 (induced by source paper "join processing for graph patterns an old dog with new tricks"):
  with members:
    - "size bounds and query plans for relational joins"
    - "constraint solving via fractional edge covers"
    - "emptyheaded boolean algebra based graph processing"
    - "transaction repair full serializability without locks"
    - "beyond worst case analysis for joins with minesweeper"
    - "skew strikes back new developments in the theory of join algorithms"
    - "optimal aggregation algorithms for middleware"

Connected through hyperedge HE-3 (induced by source paper "transaction repair full serializability without locks"):
  with members:
    - "leapfrog triejoin a worst case optimal join algorithm"

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.DB(Databases)