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: "impact vitality an indicator based on citing publications in search of excellent scientists"
  Abstract: This paper contributes to the quest for an operational definition of ‘research excellence’ and proposes a translation of the excellence concept into a bibliometric indicator. Starting from a textual analysis of funding program calls aimed at individual researchers and from the challenges for an indicator at this level in particular, a new type of indicator is proposed. The impact vitality indicator (Rons and Amez, 2008) reflects the vitality of the impact of a researcher's publication output, based on the change in volume over time of the citing publications. The introduced metric is shown to possess attractive operational characteristics and meets a number of criteria which are desirable when comparing individual researchers. The validity of one of the possible indicator variants is tested using a small dataset of applicants for a senior full-time research fellowship. Options for further research involve testing various indicator variants on larger samples linked to different kinds of evaluations. Copyright , Beech Tree Publishing.

Connected through hyperedge HE-1 (induced by source paper "h index and its alternative a review"):
  with members:
    - "restricting the h index to a publication and citation time window a case study of a timed hirsch index"
    - "a variant of the h index to measure recent performance"
    - "a review of the characteristics of 108 author level bibliometric indicators"
    - "impact vitality a measure for excellent scientists"
    - "socializing the h index"
    - "simple arithmetic versus intuitive understanding the case of the impact factor"
    - "central indexes to the citation distribution a complement to the h index"
    - "the inconsistency of the h index"

Connected through hyperedge HE-2 (induced by source paper "partition based field normalization an approach to highly specialized publication records"):
  with members:
    - "reliability and comparability of peer review results"
    - "towards a new crown indicator some theoretical considerations"
    - "normalization at the field level fractional counting of citations"
    - "caveats for the journal and field normalizations in the cwts leiden evaluations of research performance"
    - "rivals for the crown reply to opthof and leydesdorff"
    - "towards a new crown indicator an empirical analysis"

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)