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: "firefighting on trees beyond integrality gaps"
  Abstract: The Firefighter problem and a variant of it, known as Resource Minimization for Fire Containment (RMFC), are natural models for optimal inhibition of harmful spreading processes. Despite considerable progress on several fronts, the approximability of these problems is still badly understood. This is the case even when the underlying graph is a tree, which is one of the most-studied graph structures in this context and the focus of this paper. In their simplest version, a fire spreads from one fixed vertex step by step from burning to adjacent non-burning vertices, and at each time step, $B$ many non-burning vertices can be protected from catching fire. The Firefighter problem asks, for a given $B$, to maximize the number of vertices that will not catch fire, whereas RMFC (on a tree) asks to find the smallest $B$ that allows for saving all leaves of the tree. Prior to this work, the best known approximation ratios were an $O(1)$-approximation for the Firefighter problem and an $O(\log^* n)$-approximation for RMFC, both being LP-based and essentially matching the integrality gaps of two natural LP relaxations. #R##N#We improve on both approximations by presenting a PTAS for the Firefighter problem and an $O(1)$-approximation for RMFC, both qualitatively matching the known hardness results. Our results are obtained through a combination of the known LPs with several new techniques, which allow for efficiently enumerating subsets of super-constant size of a good solution to obtain stronger LPs.

Connected through hyperedge HE-1 (induced by source paper "firefighting on trees"):
  with members:
    - "3 2 firefighters are not enough"
    - "the firefighter problem with more than one firefighter on trees"

Connected through hyperedge HE-2 (induced by source paper "improved hardness for cut interdiction and firefighter problems"):
  with members:
    - "new integrality gap results for the firefighters problem on trees"
    - "fractals for kernelization lower bounds"
    - "local distribution and the symmetry gap approximability of multiway partitioning problems"
    - "interdiction problems on planar graphs"
    - "hardness of vertex deletion and project scheduling"

Connected through hyperedge HE-3 (induced by source paper "the non uniform k center problem"):
  with members:
    - "coresets for k means and k median clustering and their applications"
    - "an improved approximation for k median and positive correlation in budgeted optimization"
    - "approximating k median via pseudo approximation"

Connected through hyperedge HE-4 (induced by source paper "new integrality gap results for the firefighters problem on trees"):
  with members:
    - "the firefighter problem a structural analysis"
    - "the firefighter problem with more than one firefighter on trees"

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)