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: "reducing the rank of a matroid"
  Abstract: We consider the rank reduction problem for matroids: Given a matroid M and an integer k, find a minimum size subset of elements of M whose removal reduces the rank of M by at least k. When M is a graphical matroid this problem is the minimum k-cut problem, which admits a 2-approximation algorithm. In this paper we show that the rank reduction problem for transversal matroids is essentially at least as hard to approximate as the densest k-subgraph problem. We also prove that, while the problem is easily solvable in polynomial time for partition matroids, it is NP-hard when considering the intersection of two partition matroids. Our proof shows, in particular, that the maximum vertex cover problem is NP-hard on bipartite graphs, which answers an open problem of B. Simeone.

Connected through hyperedge HE-1 (induced by source paper "improved algorithms for mst and metric tsp interdiction"):
  with members:
    - "an o 1 approximation for minimum spanning tree interdiction"
    - "improved region growing and combinatorial algorithms for k route cut problems"

Connected through hyperedge HE-2 (induced by source paper "a parameterized algorithm for mixed cut"):
  with members:
    - "chordal editing is fixed parameter tractable"
    - "designing fpt algorithms for cut problems using randomized contractions"
    - "fixed parameter tractability of multicut in directed acyclic graphs"
    - "minimum k way cut of bounded size is fixed parameter tractable"
    - "finding small separators in linear time via treewidth reduction"
    - "fixed parameter tractability of directed multiway cut parameterized by the size of the cutset"
    - "multicut is fpt"
    - "fixed parameter tractability of multicut parameterized by the size of the cutset"

Connected through hyperedge HE-3 (induced by source paper "hardness and approximation for network flow interdiction"):
  with members:
    - "an o 1 approximation for minimum spanning tree interdiction"
    - "polynomial integrality gaps for strong sdp relaxations of densest k subgraph"
    - "approximation algorithms and hardness of the k route cut problem"

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)