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: "initial experiences re exporting duplicate and similarity computation with an oai pmh aggregator"
  Abstract: The proliferation of the Open Archive Initiative Protocol for Metadata Harvesting (OAI-PMH) has resulted in the creation of a large number of service providers, all harvesting from either data providers or aggregators. If data were available regarding the similarity of metadata records, service providers could track redundant records across harvests from multiple sources as well as provide additional end-user services. Due to the large number of metadata formats and the diverse mapping strategies employed by data providers, similarity calculation requirements necessitate the use of information retrieval strategies. We describe an OAI-PMH aggregator implementation that uses the optional “ ” container to re-export the results of similarity calculations. Metadata records (3751) were harvested from a NASA data provider and similarities for the records were computed. The results were useful for detecting duplicates, similarities and metadata errors.

Connected through hyperedge HE-1 (induced by source paper "metadata aggregation and automated digital libraries a retrospective on the nsdl experience"):
  with members:
    - "the oai data provider registration and validation service"
    - "an information network overlay architecture for the nsdl"
    - "core services in the architecture of the national digital library for science education nsdl"

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.DL(Digital Libraries)