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: "arxiv and the ref open access policy"
  Abstract: HEFCE's Policy for open access in the post-2014 Research Excellence Framework states "authors' outputs must have been deposited in an institutional or subject repository". There is no definition of a subject repository in the policy: however, there is a footnote stating: "Individuals depositing their outputs in a subject repository are advised to ensure that their chosen repository meets the requirements set out in this policy." The longest standing subject repository (or repository of any kind) is arXiv.org, established in 1991. arXiv is an open access repository of scientific research available to authors and researchers worldwide and acts as a scholarly communications forum informed and guided by scientists. Content held on arXiv is free to the end user and researchers can deposit their content freely. As of April 2018, arXiv held over 1,377,000 eprints. In some disciplines arXiv is considered essential to the sharing and publication of research. The HEFCE requirements on repositories are defined in the Information and Audit Requirements which lists the "Accepted date", the "Version of deposited file" and "available open access immediately after the publisher embargo" are expected as part of the REF submission. However, while many records in arXiv have multiple versions of work, the Author's Accepted Manuscript is not identified and there is no field to record the acceptance date of the work. Because arXiv does not capture these two specific information points it does not meet the technical requirements to be a compliant subject repository for the purposes of REF. This paper is presenting the case that articles deposited to arXiv are, in general, compliant with the requirements of the HEFCE policy. The paper summarises some work undertaken by Jisc to establish if there are other factors that can indicate the likelihood of formal compliance to the HEFCE policy.

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)