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: "are researchers that collaborate more at the international level top performers an investigation on the italian university system"
  Abstract: The practice of collaboration, and particularly international collaboration, is becoming ever more widespread in scientific research, and is likewise receiving greater interest and stimulus from policy-makers. However, the relation between research performance and degree of internationalization at the level of single researchers still presents unresolved questions. The present work, through a bibliometric analysis of the entire Italian university population working in the hard sciences over the period 2001–2005, seeks to answer some of these questions. The results show that the researchers with top performance with respect to their national colleagues are also those who collaborate more abroad, but that the reverse is not always true. Also, interesting differences emerge at the sectorial level. Finally, the effect of the nation involved in the international partnership plays a role that should not be ignored.

Connected through hyperedge HE-1 (induced by source paper "gender disparities in international research collaboration a large scale bibliometric study of 25 000 university professors"):
  with members:
    - "a gender analysis of top scientists collaboration behavior evidence from italy"
    - "academic collaboration rates and citation associations vary substantially between countries and fields"
    - "the collaboration behavior of top scientists"
    - "comparison of research productivity of italian and norwegian professors and universities"
    - "gender differences in scientific collaborations women are more egalitarian than men"
    - "gender differences in research collaboration"
    - "the relationship between scientists research performance and the degree of internationalization of their research"
    - "the contribution of star scientists to overall sex differences in research productivity"

Connected through hyperedge HE-2 (induced by source paper "the collaboration behavior of top scientists"):
  with members:
    - "measuring science irresistible temptations easy shortcuts and dangerous consequences"
    - "revisiting the scientometric conceptualization of impact and its measurement"
    - "the relationship among research productivity research collaboration and their determinants"
    - "variation in research collaboration patterns across academic ranks"
    - "how do you define and measure research productivity"
    - "individual research performance a proposal for comparing apples to oranges"
    - "the collaboration behaviors of scientists in italy a field level analysis"
    - "gender differences in research collaboration"

Connected through hyperedge HE-3 (induced by source paper "a gender analysis of top scientists collaboration behavior evidence from italy"):
  with members:
    - "the collaboration behavior of top scientists"
    - "gender differences in scientific collaborations women are more egalitarian than men"
    - "the relationship among research productivity research collaboration and their determinants"
    - "variation in research collaboration patterns across academic ranks"
    - "how do you define and measure research productivity"
    - "the collaboration behaviors of scientists in italy a field level analysis"
    - "gender differences in research collaboration"
    - "a heuristic approach to author name disambiguation in bibliometrics databases for large scale research assessments"

Connected through hyperedge HE-4 (induced by source paper "c 3 index a pagerank based multi faceted metric for authors performance measurement"):
  with members:
    - "on the discovery of success trajectories of authors"
    - "do pagerank based author rankings outperform simple citation counts"
    - "applying weighted pagerank to author citation networks"
    - "the inconsistency of the h index"
    - "pagerank for ranking authors in co citation networks"
    - "applying centrality measures to impact analysis a coauthorship network analysis"
    - "popular and or prestigious measures of scholarly esteem"

Connected through hyperedge HE-5 (induced by source paper "variation in research collaboration patterns across academic ranks"):
  with members:
    - "the impact of unproductive and top researchers on overall university research performance"
    - "the collaboration behaviors of scientists in italy a field level analysis"
    - "gender differences in research collaboration"
    - "a heuristic approach to author name disambiguation in bibliometrics databases for large scale research assessments"
    - "assessing the varying level of impact measurement accuracy as a function of the citation window length"
    - "research productivity are higher academic ranks more productive than lower ones"
    - "research collaboration and productivity is there correlation"

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)