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: "the deductive database system ldl"
  Abstract: This paper describes the LDL++ system and the research advances that have enabled its design and development. We begin by discussing the new nonmonotonic and nondeterministic constructs that extend the functionality of the LDL++ language, while preserving its model-theoretic and fixpoint semantics. Then, we describe the execution model and the open architecture designed to support these new constructs and to facilitate the integration with existing DBMSs and applications. Finally, we describe the lessons learned by using LDL++ on various tested applications, such as middleware and datamining.

Connected through hyperedge HE-1 (induced by source paper "scaling up reasoning and advanced analytics on bigdata"):
  with members:
    - "vicious circle principle and logic programs with aggregates"
    - "clingo asp control preliminary report"
    - "efficient computation of the well founded semantics over big data"
    - "scaling datalog for machine learning on big data"
    - "multi core processors an overview"
    - "relational transducers for declarative networking"
    - "xsb extending prolog with tabled logic programming"
    - "the dlv system for knowledge representation and reasoning"

Connected through hyperedge HE-2 (induced by source paper "top down and bottom up evaluation procedurally integrated"):
  with members:
    - "efficient instance retrieval of subgoals for subsumptive tabled evaluation of logic programs"
    - "the language features and architecture of b prolog"
    - "xsb extending prolog with tabled logic programming"

Connected through hyperedge HE-3 (induced by source paper "improving the deductive system des with persistence by using sql dbms s"):
  with members:
    - "xsb extending prolog with tabled logic programming"
    - "experimenting with recursive queries in database and logic programming systems"
    - "the dlv system for knowledge representation and reasoning"
    - "smodels a system for answer set programming"

Connected through hyperedge HE-4 (induced by source paper "experimenting with recursive queries in database and logic programming systems"):
  with members:
    - "the dlv system for knowledge representation and reasoning"
    - "smodels a system for answer set programming"

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)