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: "a reduction system for optimal 1 planar graphs"
  Abstract: There is a graph reduction system so that every optimal 1-planar graph can be reduced to an irreducible extended wheel graph, provided the reductions are applied such that the given graph class is preserved. A graph is optimal 1-planar if it can be drawn in the plane with at most one crossing per edge and is optimal if it has the maximum of 4n-8 edges. #R##N#We show that the reduction system is context-sensitive so that the preservation of the graph class can be granted by local conditions which can be tested in constant time. Every optimal 1-planar graph G can be reduced to every extended wheel graph whose size is in a range from the (second) smallest one to some upper bound that depends on G. There is a reduction to the smallest extended wheel graph if G is not 5-connected, but not conversely. The reduction system has side effects and is non-deterministic and non-confluent. Nevertheless, reductions can be computed in linear time.

Connected through hyperedge HE-1 (induced by source paper "recognizing optimal 1 planar graphs in linear time"):
  with members:
    - "parameterized complexity of 1 planarity"
    - "recognizing and drawing ic planar graphs"
    - "on 4 map graphs and 1 planar graphs and their recognition problem"
    - "on the recognition of fan planar and maximal outer fan planar graphs"
    - "adding one edge to planar graphs makes crossing number and 1 planarity hard"
    - "the straight line rac drawing problem is np hard"

Connected through hyperedge HE-2 (induced by source paper "recognizing ic planar and nic planar graphs"):
  with members:
    - "parameterized complexity of 1 planarity"
    - "recognizing optimal 1 planar graphs in linear time"
    - "recognizing and drawing ic planar graphs"
    - "on 4 map graphs and 1 planar graphs and their recognition problem"
    - "1 visibility representations of 1 planar graphs"
    - "adding one edge to planar graphs makes crossing number and 1 planarity hard"

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.CG(Computational Geometry)