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: "obtaining a bipartite graph by contracting few edges"
  Abstract: We initiate the study of the Bipartite Contraction problem from the perspective of parameterized complexity. In this problem we are given a graph $G$ and an integer $k$, and the task is to determine whether we can obtain a bipartite graph from $G$ by a sequence of at most $k$ edge contractions. Our main result is an $f(k) n^{O(1)}$ time algorithm for Bipartite Contraction. Despite a strong resemblance between Bipartite Contraction and the classical Odd Cycle Transversal (OCT) problem, the methods developed to tackle OCT do not seem to be directly applicable to Bipartite Contraction. Our algorithm is based on a novel combination of the irrelevant vertex technique, introduced by Robertson and Seymour, and the concept of important separators. Both techniques have previously been used as key components of algorithms for fundamental problems in parameterized complexity. However, to the best of our knowledge, this is the first time the two techniques are applied in unison.

Connected through hyperedge HE-1 (induced by source paper "contracting to a longest path in h free graphs"):
  with members:
    - "on the parameterized complexity of contraction to generalization of trees"
    - "independent feedback vertex set for p_5 free graphs"
    - "contracting bipartite graphs to paths and cycles"
    - "polynomial time algorithms for the longest induced path and induced disjoint paths problems on graphs of bounded mim width"
    - "a faster fpt algorithm for bipartite contraction"
    - "obtaining planarity by contracting few edges"
    - "finding small separators in linear time via treewidth reduction"
    - "contracting graphs to paths and trees"

Connected through hyperedge HE-2 (induced by source paper "contraction and deletion blockers for perfect graphs and h free graphs"):
  with members:
    - "critical vertices and edges in h free graphs"
    - "hadwiger number of graphs with small chordality"
    - "kernels for below upper bound parameterizations of the hitting set and directed dominating set problems"

Connected through hyperedge HE-3 (induced by source paper "an improved kernel for the cycle contraction problem"):
  with members:
    - "a faster fpt algorithm for bipartite contraction"
    - "obtaining planarity by contracting few edges"
    - "contracting graphs to paths and trees"

Connected through hyperedge HE-4 (induced by source paper "a faster fpt algorithm for bipartite contraction"):
  with members:
    - "linear time parameterized algorithms via skew symmetric multicuts"
    - "linear time fpt algorithms via network flow"
    - "interval deletion is fixed parameter tractable"
    - "faster parameterized algorithms using linear programming"
    - "obtaining planarity by contracting few edges"
    - "on group feedback vertex set parameterized by the size of the cutset"
    - "representative sets and irrelevant vertices new tools for kernelization"
    - "finding small separators in linear time via treewidth reduction"

Connected through hyperedge HE-5 (induced by source paper "a single exponential fpt algorithm for the k_4 minor cover problem"):
  with members:
    - "slightly superexponential parameterized problems"
    - "solving connectivity problems parameterized by treewidth in single exponential time"
    - "hitting forbidden minors approximation and kernelization"
    - "cutset sampling for bayesian networks"

Connected through hyperedge HE-6 (induced by source paper "obtaining planarity by contracting few edges"):
  with members:
    - "msol restricted contractibility to planar graphs"
    - "finding small separators in linear time via treewidth reduction"
    - "contracting graphs to paths and trees"
    - "obtaining a planar graph by vertex deletion"

Connected through hyperedge HE-7 (induced by source paper "msol restricted contractibility to planar graphs"):
  with members:
    - "obtaining planarity by contracting few edges"
    - "obtaining a planar graph by vertex deletion"
    - "computing crossing numbers in quadratic time"

Connected through hyperedge HE-8 (induced by source paper "finding small separators in linear time via treewidth reduction"):
  with members:
    - "contracting graphs to paths and trees"
    - "on multiway cut parameterized above lower bounds"
    - "multicut is fpt"
    - "fixed parameter tractability of multicut parameterized by the size of the cutset"
    - "treewidth reduction for constrained separation and bipartization problems"
    - "almost 2 sat is fixed parameter tractable"
    - "minimum cost homomorphisms to reflexive digraphs"
    - "minimum cost homomorphisms to proper interval graphs and bigraphs"

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)