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: "cited half life of the journal literature"
  Abstract: Analyzing 13,455 journals listed in the Journal Citation Report (Thomson Reuters) from 1997 through 2013, we report that the mean cited half-life of the scholarly literature is 6.5 years and growing at a rate of 0.13 years per annum. Focusing on a subset of journals (N=4,937) for which we have a continuous series of half-life observations, 209 of 229 (91%) subject categories experienced increasing cited half-lives. Contrary to the overall trend, engineering and chemistry journals experienced declining cited half-lives. Last, as journals attracted more citations, a larger proportion of them were directed toward older papers. The trend to cite older papers is not fully explained by technology (digital publishing, search and retrieval, etc.), but may be the result of a structural shift to fund incremental and applied research over fundamental science.

Connected through hyperedge HE-1 (induced by source paper "back to the past on the shoulders of an academic search engine giant"):
  with members:
    - "methods for estimating the size of google scholar"
    - "the silent fading of an academic search engine the case of microsoft academic search"
    - "does google scholar contain all highly cited documents 1950 2013"
    - "on the shoulders of giants the growing impact of older articles"
    - "google scholar metrics evolution an analysis according to languages"

Connected through hyperedge HE-2 (induced by source paper "national research impact indicators from mendeley readers"):
  with members:
    - "the vqr italy s second national research assessment methodological failures and ranking distortions"
    - "field normalized citation impact indicators and the choice of an appropriate counting method"
    - "tweets vs mendeley readers how do these two social media metrics differ"
    - "do altmetrics correlate with citations extensive comparison of altmetric indicators with citations from a multidisciplinary perspective"
    - "tweets as impact indicators examining the implications of automated bot accounts on twitter"
    - "how well developed are altmetrics a cross disciplinary analysis of the presence of alternative metrics in scientific publications"
    - "a comparison between two main academic literature collections web of science and scopus databases"
    - "the leiden ranking 2011 2012 data collection indicators and interpretation"

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)