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: "exponential time approximation of hard problems"
  Abstract: We study optimization problems that are neither approximable in polynomial time (at least with a constant factor) nor fixed parameter tractable, under widely believed complexity assumptions. Specifically, we focus on Maximum Independent Set, Vertex Coloring, Set Cover, and Bandwidth. #R##N#In recent years, many researchers design exact exponential-time algorithms for these and other hard problems. The goal is getting the time complexity still of order $O(c^n)$, but with the constant $c$ as small as possible. In this work we extend this line of research and we investigate whether the constant $c$ can be made even smaller when one allows constant factor approximation. In fact, we describe a kind of approximation schemes -- trade-offs between approximation factor and the time complexity. #R##N#We study two natural approaches. The first approach consists of designing a backtracking algorithm with a small search tree. We present one result of that kind: a $(4r-1)$-approximation of Bandwidth in time $O^*(2^{n/r})$, for any positive integer $r$. #R##N#The second approach uses general transformations from exponential-time exact algorithms to approximations that are faster but still exponential-time. For example, we show that for any reduction rate $r$, one can transform any $O^*(c^n)$-time algorithm for Set Cover into a $(1+\ln r)$-approximation algorithm running in time $O^*(c^{n/r})$. We believe that results of that kind extend the applicability of exact algorithms for NP-hard problems.

Connected through hyperedge HE-1 (induced by source paper "improved in approximability bounds for d scattered set"):
  with members:
    - "kernelization and approximation of distance r independent sets on nowhere dense graphs"
    - "structurally parameterized d scattered set"
    - "on distance d independent set and other problems in graphs with few minimal separators"
    - "time approximation trade offs for inapproximable problems"
    - "optimal parameterized algorithms for planar facility location problems using voronoi diagrams"
    - "independent set induced matching and pricing connections and tight subexponential time approximation hardnesses"
    - "bidimensionality and eptas"

Connected through hyperedge HE-2 (induced by source paper "on subexponential running times for approximating directed steiner tree and related problems"):
  with members:
    - "new tools and connections for exponential time approximation"
    - "sub exponential approximation schemes for csps from dense to almost sparse"
    - "analytical approach to parallel repetition"
    - "independent set induced matching and pricing connections and tight subexponential time approximation hardnesses"

Connected through hyperedge HE-3 (induced by source paper "new tools and connections for exponential time approximation"):
  with members:
    - "from gap eth to fpt inapproximability clique dominating set and more"
    - "a birthday repetition theorem and complexity of approximating dense csps"
    - "time approximation trade offs for inapproximable problems"
    - "sparsification and subexponential approximation"
    - "independent set induced matching and pricing connections and tight subexponential time approximation hardnesses"

Connected through hyperedge HE-4 (induced by source paper "sparsification and subexponential approximation"):
  with members:
    - "multi parameter complexity analysis for constrained size graph problems using greediness for parameterization"
    - "fixed parameter and approximation algorithms a new look"
    - "independent set induced matching and pricing connections and tight subexponential time approximation hardnesses"
    - "an exponential time 2 approximation algorithm for bandwidth"

Connected through hyperedge HE-5 (induced by source paper "independent set induced matching and pricing connections and tight subexponential time approximation hardnesses"):
  with members:
    - "completely inapproximable monotone and antimonotone parameterized problems"
    - "on problems as hard as cnf sat"
    - "fixed parameter and approximation algorithms a new look"
    - "graph pricing problem on bounded treewidth bounded genus and k partite graphs"
    - "subexponential and fpt time inapproximability of independent set and related problems"
    - "graph products revisited tight approximation hardness of induced matching poset dimension and more"
    - "algorithmic pricing via virtual valuations"
    - "minimizing flow time in the wireless gathering problem"

Connected through hyperedge HE-6 (induced by source paper "an exponential time 2 approximation algorithm for bandwidth"):
  with members:
    - "bandwidth and distortion revisited"
    - "even faster exact bandwidth"

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.DS(Data Structures and Algorithms)