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: "a polynomial time approximation scheme for the airplane refueling problem"
  Abstract: We study the airplane refueling problem which was introduced by the physicists Gamow and Stern in their classical book Puzzle-Math (1958). Sticking to the original story behind this problem, suppose we have to deliver a bomb in some distant point of the globe, the distance being much greater than the range of any individual airplane at our disposal. Therefore, the only feasible option to carry out this mission is to better utilize our fleet via mid-air refueling. Starting with several airplanes that can refuel one another, and gradually drop out of the flight until the single plane carrying the bomb reaches the target, how would you plan the refueling policy? #R##N#The main contribution of Gamow and Stern was to provide a complete characterization of the optimal refueling policy for the special case of identical airplanes. In spite of their elegant and easy-to-analyze solution, the computational complexity of the general airplane refueling problem, with arbitrary tank volumes and consumption rates, has remained widely open ever since, as recently pointed out by Woeginger (Open Problems in Scheduling, Dagstuhl 2010, page 24). To our knowledge, other than a logarithmic approximation, which can be attributed to folklore, it is not entirely obvious even if constant-factor performance guarantees are within reach. #R##N#In this paper, we propose a polynomial-time approximation scheme for the airplane refueling problem in its utmost generality. Our approach builds on a novel combination of ideas related to parametric pruning, efficient guessing tricks, reductions to well-structured instances of generalized assignment, and additional insight into how LP-rounding algorithms in this context actually work. We complement this result by presenting a fast and easy-to-implement algorithm that approximates the optimal refueling policy to within a constant factor.

Connected through hyperedge HE-1 (induced by source paper "a fast exact algorithm for airplane refueling problem"):
  with members:
    - "a primal dual approximation algorithm for min sum single machine scheduling problems"
    - "how unsplittable flow covering helps scheduling with job dependent cost functions"
    - "the local global conjecture for scheduling with non linear cost"
    - "dual techniques for scheduling on a machine with varying speed"
    - "the geometry of scheduling"

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)