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: "a practical ontology for the large scale modeling of scholarly artifacts and their usage"
  Abstract: The large-scale analysis of scholarly artifact usage is constrained primarily by current practices in usage data archiving, privacy issues concerned with the dissemination of usage data, and the lack of a practical ontology for modeling the usage domain. As a remedy to the third constraint, this article presents a scholarly ontology that was engineered to represent those classes for which large-scale bibliographic and usage data exists, supports usage research, and whose instantiation is scalable to the order of 50 million articles along with their associated artifacts (e.g. authors and journals) and an accompanying 1 billion usage events. The real world instantiation of the presented abstract ontology is a semantic network model of the scholarly community which lends the scholarly process to statistical analysis and computational support. We present the ontology, discuss its instantiation, and provide some example inference rules for calculating various scholarly artifact metrics.

Connected through hyperedge HE-1 (induced by source paper "general purpose computing on a semantic network substrate"):
  with members:
    - "grammar based random walkers in semantic networks"
    - "using rdf to model the structure and process of systems"

Connected through hyperedge HE-2 (induced by source paper "a recommender system to support the scholarly communication process"):
  with members:
    - "exposing multi relational networks to single relational network analysis algorithms"
    - "automatic metadata generation using associative networks"
    - "grammar based random walkers in semantic networks"
    - "an algorithm to determine peer reviewers"
    - "towards usage based impact metrics first results from the mesur project"
    - "a multi relational network to support the scholarly communication process"

Connected through hyperedge HE-3 (induced by source paper "towards usage based impact metrics first results from the mesur project"):
  with members:
    - "usage impact factor the effects of sample characteristics on usage based impact metrics"
    - "worldwide use and impact of the nasa astrophysics data system digital library"
    - "earlier web usage statistics as predictors of later citation impact"
    - "the bibliometric properties of article readership information"
    - "toward alternative metrics of journal impact a comparison of download and citation data"

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)