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: "lower bounds for approximation schemes for closest string"
  Abstract: In the Closest String problem one is given a family $\mathcal S$ of equal-length strings over some fixed alphabet, and the task is to find a string $y$ that minimizes the maximum Hamming distance between $y$ and a string from $\mathcal S$. While polynomial-time approximation schemes (PTASes) for this problem are known for a long time [Li et al., J. ACM'02], no efficient polynomial-time approximation scheme (EPTAS) has been proposed so far. In this paper, we prove that the existence of an EPTAS for Closest String is in fact unlikely, as it would imply that $\mathrm{FPT}=\mathrm{W}[1]$, a highly unexpected collapse in the hierarchy of parameterized complexity classes. Our proof also shows that the existence of a PTAS for Closest String with running time $f(\varepsilon)\cdot n^{o(1/\varepsilon)}$, for any computable function $f$, would contradict the Exponential Time Hypothesis.

Connected through hyperedge HE-1 (induced by source paper "parameterized approximation schemes for independent set of rectangles and geometric knapsack"):
  with members:
    - "approximating geometric knapsack via l packings"
    - "on approximating maximum independent set of rectangles"
    - "fixed parameter approximations for k center problems in low highway dimension graphs"
    - "a fixed parameter tractable approximation scheme for the optimal cut graph of a surface"
    - "the constant inapproximability of the parameterized dominating set problem"
    - "parameterized approximability of maximizing the spread of influence in networks"
    - "parameterized approximation schemes using graph widths"
    - "approximation schemes for maximum weight independent set of rectangles"

Connected through hyperedge HE-2 (induced by source paper "low rank binary matrix approximation in column sum norm"):
  with members:
    - "approximation schemes for low rank binary matrix approximation problems"
    - "on the complexity of robust pca and l1 norm low rank matrix approximation"
    - "parameterized low rank binary matrix approximation"
    - "on low rank approximation of binary matrices"
    - "sketching as a tool for numerical linear algebra"
    - "randomized algorithms for matrices and data"
    - "on the closest string and substring problems"

Connected through hyperedge HE-3 (induced by source paper "on computing centroids according to the p norms of hamming distance vectors"):
  with members:
    - "collective schedules scheduling meets computational social choice"
    - "committee scoring rules axiomatic characterization and hierarchy"
    - "a generalization of the minisum and minimax voting methods"
    - "a note on clustering aggregation"
    - "combinatorial n fold integer programming and applications"
    - "solving the closest vector problem in 2 n time the discrete gaussian strikes again"
    - "enumerative lattice algorithms in any norm via m ellipsoid coverings"

Connected through hyperedge HE-4 (induced by source paper "model checking on ordered structures"):
  with members:
    - "order invariance on decomposable structures"
    - "successor invariant first order logic on graphs with excluded topological subgraphs"
    - "model checking existential logic on partially ordered sets"
    - "deciding first order properties of nowhere dense graphs"
    - "courcelle s theorem a game theoretic approach"
    - "lower bounds for the complexity of monadic second order logic"
    - "deciding first order properties of locally tree decomposable structures"

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)