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: "citation advantage for oa self archiving is independent of journal impact factor article age and number of co authors"
  Abstract: Eysenbach has suggested that the OA (Green) self-archiving advantage might just be an artifact of potential uncontrolled confounding factors such as article age (older articles may be both more cited and more likely to be self-archived), number of authors (articles with more authors might be more cited and more self-archived), subject matter (the subjects that are cited more, self-archive more), country (same thing), number of authors, citation counts of authors, etc. Chawki Hajjem (doctoral candidate, UQaM) had already shown that the OA advantage was present in all cases when articles were analysed separately by age, subject matter or country. He has now done a multiple regression analysis jointly testing (1) article age, (2) journal impact factor, (3) number of authors, and (4) OA self-archiving as separate factors for 442,750 articles in 576 (biomedical) journals across 11 years, and has shown that each of the four factors contributes an independent, statistically significant increment to the citation counts. The OA-self-archiving advantage remains a robust, independent factor. Having successfully responded to his challenge, we now challenge Eysenbach to demonstrate -- by testing a sufficiently broad and representative sample of journals at all levels of the journal quality, visibility and prestige hierarchy -- that his finding of a citation advantage for Gold OA (articles published OA on the high-profile website of the only journal he tested (PNAS) over Green OA articles in the same journal (self-archived on the author's website) was not just an artifact of having tested only one very high-profile journal.

Connected through hyperedge HE-1 (induced by source paper "confirmation bias and the open access advantage some methodological suggestions for the davis citation study"):
  with members:
    - "author choice open access publishing in the biological and medical literature a citation analysis"
    - "does the arxiv lead to higher citations and reduced publisher downloads for mathematics articles"
    - "the open access citation advantage quality advantage or quality bias"
    - "open access does not increase citations for research articles from the astrophysical journal"
    - "ten year cross disciplinary comparison of the growth of open access and how it increases research citation impact"
    - "the effect of use and access on citations"

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.IR(Information Retrieval)