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: "unsolved problems in visibility graphs of points segments and polygons"
  Abstract: In this survey paper, we present open problems and conjectures on visibility graphs of points, segments and polygons along with necessary backgrounds for understanding them.

Connected through hyperedge HE-1 (induced by source paper "the parameterized complexity of guarding almost convex polygons"):
  with members:
    - "a ptas for vertex guarding weakly visible polygons an extended abstract"
    - "constant approximation algorithms for guarding simple polygons using vertex guards"
    - "irrational guards are sometimes needed"
    - "an approximation algorithm for the art gallery problem"
    - "engineering art galleries"
    - "approximability of guarding weak visibility polygons"
    - "a new upper bound for the vc dimension of visibility regions"
    - "improved approximation for guarding simple galleries from the perimeter"

Connected through hyperedge HE-2 (induced by source paper "pseudo triangle visibility graph characterization and reconstruction"):
  with members:
    - "recognition and complexity of point visibility graphs"
    - "some results on point visibility graphs"

Connected through hyperedge HE-3 (induced by source paper "advancing through terrains"):
  with members:
    - "orthogonal terrain guarding is np complete"

Connected through hyperedge HE-4 (induced by source paper "computational complexity aspects of point visibility graphs"):
  with members:
    - "on colouring point visibility graphs"
    - "recognition and complexity of point visibility graphs"
    - "finding points in general position"
    - "some results on point visibility graphs"

Connected through hyperedge HE-5 (induced by source paper "grid obstacle representation of graphs"):
  with members:
    - "computing the obstacle number of a plane graph"

Connected through hyperedge HE-6 (induced by source paper "on colouring point visibility graphs"):
  with members:
    - "partitions of planar point sets into polygons"
    - "recognition and complexity of point visibility graphs"
    - "point visibility graph recognition is np hard"
    - "some results on point visibility graphs"

Connected through hyperedge HE-7 (induced by source paper "obstructing visibilities with one obstacle"):
  with members:
    - "recognition and complexity of point visibility graphs"
    - "graphs with plane outside obstacle representations"
    - "convex obstacle numbers of outerplanar graphs and bipartite permutation graphs"

Connected through hyperedge HE-8 (induced by source paper "partitions of planar point sets into polygons"):
  with members:
    - "recognition and complexity of point visibility graphs"
    - "some results on point visibility graphs"

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)