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: "constant approximation algorithms for guarding simple polygons using vertex guards"
  Abstract: The art gallery problem enquires about the least number of guards sufficient to ensure that an art gallery, represented by a polygon $P$, is fully guarded. Most standard versions of this problem are known to be NP-hard. In 1987, Ghosh provided a deterministic $\mathcal{O}(\log n)$-approximation algorithm for the case of vertex guards and edge guards in simple polygons. In the same paper, Ghosh also conjectured the existence of constant ratio approximation algorithms for these problems. We present here three polynomial-time algorithms with a constant approximation ratio for guarding an $n$-sided simple polygon $P$ using vertex guards. (i) The first algorithm, that has an approximation ratio of 18, guards all vertices of $P$ in $\mathcal{O}(n^4)$ time. (ii) The second algorithm, that has the same approximation ratio of 18, guards the entire boundary of $P$ in $\mathcal{O}(n^5)$ time. (iii) The third algorithm, that has an approximation ratio of 27, guards all interior and boundary points of $P$ in $\mathcal{O}(n^5)$ time. The significance of our results lies in the fact that these results settle the conjecture by Ghosh regarding the existence of constant-factor approximation algorithms for this problem, which has been open since 1987 despite several attempts by researchers. Our approximation algorithms exploit several deep visibility structures of simple polygons which are interesting in their own right.

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"
    - "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"
    - "unsolved problems in visibility graphs of points segments and polygons"

Connected through hyperedge HE-2 (induced by source paper "routing in histograms"):
  with members:
    - "plane hop spanners for unit disk graphs simpler and better"
    - "routing in unit disk graphs"
    - "routing in polygonal domains"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"
    - "new routing techniques and their applications"
    - "competitive local routing with constraints"
    - "approximability of guarding weak visibility polygons"

Connected through hyperedge HE-3 (induced by source paper "a constant factor approximation algorithm for vertex guarding a wv polygon"):
  with members:
    - "a ptas for vertex guarding weakly visible polygons an extended abstract"
    - "an approximation algorithm for the art gallery problem"
    - "the continuous 1 5d terrain guarding problem discretization optimal solutions and ptas"
    - "approximability of guarding weak visibility polygons"
    - "improved approximation for guarding simple galleries from the perimeter"

Connected through hyperedge HE-4 (induced by source paper "smoothed analysis of the art gallery problem"):
  with members:
    - "beyond worst case analysis"
    - "the complexity of drawing a graph in a polygonal region"
    - "a friendly smoothed analysis of the simplex method"
    - "irrational guards are sometimes needed"
    - "intersection graphs of rays and grounded segments"
    - "an approximation algorithm for the art gallery problem"
    - "the continuous 1 5d terrain guarding problem discretization optimal solutions and ptas"
    - "recognition and complexity of 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)