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: "contracting graphs to paths and trees"
  Abstract: Vertex deletion and edge deletion problems play a central role in Parameterized Complexity. Examples include classical problems like Feedback Vertex Set, Odd Cycle Transversal, and Chordal Deletion. Interestingly, the study of edge contraction problems of this type from a parameterized perspective has so far been left largely unexplored. We consider two basic edge contraction problems, which we call Path-Contractibility and Tree-Contractibility. Both problems take an undirected graph $G$ and an integer $k$ as input, and the task is to determine whether we can obtain a path or an acyclic graph, respectively, by contracting at most $k$ edges of $G$. Our main contribution is an algorithm with running time $4^{k+O(\log^2 k)} + n^{O(1)}$ for Path-Contractibility and an algorithm with running time $4.88^k n^{O(1)}$ for Tree-Contractibility, based on a novel application of the color coding technique of Alon, Yuster and Zwick. Furthermore, we show that Path-Contractibility has a kernel with at most $5k+3$ vertices, while Tree-Contractibility does not have a polynomial kernel unless coNP $\subseteq$ NP/poly. We find the latter result surprising, because of the strong connection between Tree-Contractibility and Feedback Vertex Set, which is known to have a vertex kernel with size $O(k^2)$.

Connected through hyperedge HE-1 (induced by source paper "multistage graph problems on a global budget"):
  with members:
    - "multistage vertex cover"
    - "temporal matching"
    - "computing maximum matchings in temporal graphs"
    - "online multistage subset maximization problems"
    - "multistage knapsack"
    - "changing bases multistage optimization for matroids and matchings"
    - "facility location in evolving metrics"

Connected through hyperedge HE-2 (induced by source paper "multistage problems on a global budget"):
  with members:
    - "multistage vertex cover"
    - "online multistage subset maximization problems"
    - "multistage knapsack"
    - "changing bases multistage optimization for matroids and matchings"
    - "facility location in evolving metrics"

Connected through hyperedge HE-3 (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"
    - "obtaining a bipartite graph by contracting few edges"

Connected through hyperedge HE-4 (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"
    - "obtaining a bipartite graph by contracting few edges"

Connected through hyperedge HE-5 (induced by source paper "hadwiger number of graphs with small chordality"):
  with members:
    - "finding large clique minors is hard"

Connected through hyperedge HE-6 (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-7 (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"
    - "obtaining a bipartite graph by contracting few edges"
    - "obtaining a planar graph by vertex deletion"

Connected through hyperedge HE-8 (induced by source paper "finding small separators in linear time via treewidth reduction"):
  with members:
    - "obtaining a bipartite graph by contracting few edges"
    - "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)