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: "the field standardized average impact of national research systems compared to world average the case of italy"
  Abstract: The study presents a time-series analysis of field-standardized average impact of Italian research compared to the world average. The approach is purely bibliometric, based on census of the full scientific production from all Italian public research organizations active in 2001---2006 (hard sciences only). The analysis is conducted both at sectorial level (aggregated, by scientific discipline and for single fields within disciplines) and at organizational level (by type of organization and for single organizations). The essence of the methodology should be replicable in all other national contexts. Its offers support to policy-makers and administrators for strategic analysis aimed at identifying strengths and weaknesses of national research systems and institutions.

Connected through hyperedge HE-1 (induced by source paper "the ratio of top scientists to the academic staff as an indicator of the competitive strength of universities"):
  with members:
    - "measuring science irresistible temptations easy shortcuts and dangerous consequences"
    - "the impact of unproductive and top researchers on overall university research performance"
    - "from rankings to funnel plots the question of accounting for uncertainty when assessing university research performance"
    - "ranking research institutions by the number of highly cited articles per scientist"
    - "the determinants of academic career advancement evidence from italy"
    - "which of the world s institutions employ the most highly cited researchers an analysis of the data from highlycited com"
    - "how do you define and measure research productivity"
    - "variability of research performance across disciplines within universities in non competitive higher education systems"

Connected through hyperedge HE-2 (induced by source paper "the spin off of elite universities in non competitive undifferentiated higher education systems an empirical simulation in italy"):
  with members:
    - "revisiting size effects in higher education research productivity"
    - "the dispersion of research performance within and between universities as a potential indicator of the competitive intensity in higher education systems"
    - "a heuristic approach to author name disambiguation in bibliometrics databases for large scale research assessments"
    - "national scale research performance assessment at the individual level"
    - "research productivity are higher academic ranks more productive than lower ones"
    - "the dangers of performance based research funding in non competitive higher education systems"

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)