human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "data mining the foundational patents of photovoltaic materials an application of patent citation spectroscopy"):
  Abstract: We apply Patent Citation Spectroscopy (PCS)--originally developed as Reference Publication Year Spectroscopy for studying landmarks and milestones in scientific literature--to patent literature classified into the nine Y-subclasses of the Cooperative Patent Classification (CPC) that describe material photovoltaic technologies. For this study we extended the routine with the option to use the advanced search queries at PatentsView. On the basis of two normalizations of the longitudinal distribution of the publication years of the patents cited by the retrieved patents, the routine (at this http URL) provides a best guess of the foundational patent for the subject specified in the string. In five of the nine cases, we found corroborating evidence for the foundational character of the patent indicated by the routine.

Includes members:
  Member "strategic intelligence on emerging technologies scientometric overlay mapping":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "mapping patent classifications portfolio and statistical analysis and the comparison of strengths and weaknesses")
  Member "patent citation spectroscopy pcs algorithmic retrieval of landmark patents":
    also connected through other hyperedges:
      (none)
  Member "citation algorithms for identifying research milestones driving biomedical innovation":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "early identification of important patents design and validation of citation network metrics")
  Member "introducing citedreferencesexplorer crexplorer a program for reference publication year spectroscopy with cited references standardization":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "how to identify the roots of broad research topics and fields the introduction of rpys sampling using the example of climate change research")
  Member "patents as instruments for exploring innovation dynamics geographic and technological perspectives on photovoltaic cells":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "mapping patent classifications portfolio and statistical analysis and the comparison of strengths and weaknesses")
  Member "detecting the historical roots of research fields by reference publication year spectroscopy rpys":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "how to identify the roots of broad research topics and fields the introduction of rpys sampling using the example of climate change research")
  Member "publish or patent bibliometric evidence for empirical trade offs in national funding strategies":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "the relative influences of government funding and international collaboration on citation impact")

Question: Please tell me which class the source paper 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)