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: "evidence of open access of scientific publications in google scholar a large scale analysis"
  Abstract: This article uses Google Scholar (GS) as a source of data to analyse Open Access (OA) levels across all countries and fields of research. All articles and reviews with a DOI and published in 2009 or 2014 and covered by the three main citation indexes in the Web of Science (2,269,022 documents) were selected for study. The links to freely available versions of these documents displayed in GS were collected. To differentiate between more reliable (sustainable and legal) forms of access and less reliable ones, the data extracted from GS was combined with information available in DOAJ, CrossRef, OpenDOAR, and ROAR. This allowed us to distinguish the percentage of documents in our sample that are made OA by the publisher (23.1%, including Gold, Hybrid, Delayed, and Bronze OA) from those available as Green OA (17.6%), and those available from other sources (40.6%, mainly due to ResearchGate). The data shows an overall free availability of 54.6%, with important differences at the country and subject category levels. The data extracted from GS yielded very similar results to those found by other studies that analysed similar samples of documents, but employed different methods to find evidence of OA, thus suggesting a relative consistency among methods.

Connected through hyperedge HE-1 (induced by source paper "who pays comparing cost sharing models for a gold open access publication environment"):
  with members:
    - "the state of open access in germany an analysis of the publication output of german universities"
    - "constructing bibliometric networks a comparison between full and fractional counting"
    - "green and gold open access percentages and growth by discipline"

Connected through hyperedge HE-2 (induced by source paper "indicators of open access for universities"):
  with members:
    - "developing indicators on open access by combining evidence from diverse data sources"
    - "disentangling gold open access"
    - "the leiden ranking 2011 2012 data collection indicators and interpretation"

Connected through hyperedge HE-3 (induced by source paper "coverage of highly cited documents in google scholar web of science and scopus a multidisciplinary comparison"):
  with members:
    - "google scholar as a data source for research assessment"
    - "can we use google scholar to identify highly cited documents"
    - "the accuracy of confidence intervals for field normalised indicators"
    - "three practical field normalised alternative indicator formulae for research evaluation"
    - "a two sided academic landscape portrait of highly cited documents in google scholar 1950 2013"
    - "the journal coverage of web of science and scopus a comparative analysis"
    - "methods for estimating the size of google scholar"
    - "a new methodology for comparing google scholar and scopus"

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)