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: "hardness and approximation for network flow interdiction"
  Abstract: In the Network Flow Interdiction problem an adversary attacks a network in order to minimize the maximum s-t-flow. Very little is known about the approximatibility of this problem despite decades of interest in it. We present the first approximation hardness, showing that Network Flow Interdiction and several of its variants cannot be much easier to approximate than Densest k-Subgraph. In particular, any $n^{o(1)}$-approximation algorithm for Network Flow Interdiction would imply an $n^{o(1)}$-approximation algorithm for Densest k-Subgraph. We complement this hardness results with the first approximation algorithm for Network Flow Interdiction, which has approximation ratio 2(n-1). We also show that Network Flow Interdiction is essentially the same as the Budgeted Minimum s-t-Cut problem, and transferring our results gives the first approximation hardness and algorithm for that problem, as well.

Connected through hyperedge HE-1 (induced by source paper "downgrading to minimize connectivity"):
  with members:
    - "improved algorithms for mst and metric tsp interdiction"
    - "simple and fast rounding algorithms for directed and node weighted multiway cut"
    - "an o 1 approximation for minimum spanning tree interdiction"
    - "improved region growing and combinatorial algorithms for k route cut problems"
    - "multiway cut pairwise realizable distributions and descending thresholds"
    - "approximation algorithms and hardness of the k route cut problem"

Connected through hyperedge HE-2 (induced by source paper "on the robustness of distributed computing networks"):
  with members:
    - "multi commodity flow with in network processing"

Connected through hyperedge HE-3 (induced by source paper "the complexity of computing a robust flow"):
  with members:
    - "robust flows over time models and complexity results"
    - "rerouting flows when links fail"
    - "protection of flows under targeted attacks"
    - "on the power of randomization in network interdiction"

Connected through hyperedge HE-4 (induced by source paper "protection of flows under targeted attacks"):
  with members:
    - "the complexity of computing a robust flow"
    - "on the power of randomization in network interdiction"
    - "abstract flows over time a first step towards solving dynamic packing problems"

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)