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: "towards tight bounds on theta graphs"
  Abstract: We present improved upper and lower bounds on the spanning ratio of $\theta$-graphs with at least six cones. Given a set of points in the plane, a $\theta$-graph partitions the plane around each vertex into $m$ disjoint cones, each having aperture $\theta=2\pi/m$, and adds an edge to the `closest' vertex in each cone. We show that for any integer $k \geq 1$, $\theta$-graphs with $4k+2$ cones have a spanning ratio of $1+2\sin(\theta/2)$ and we provide a matching lower bound, showing that this spanning ratio tight. #R##N#Next, we show that for any integer $k \geq 1$, $\theta$-graphs with $4k+4$ cones have spanning ratio at most $1+2\sin(\theta/2)/(\cos(\theta/2)-\sin(\theta/2))$. We also show that $\theta$-graphs with $4k+3$ and $4k+5$ cones have spanning ratio at most $\cos(\theta/4)/(\cos(\theta/2)-\sin(3\theta/4))$. This is a significant improvement on all families of $\theta$-graphs for which exact bounds are not known. For example, the spanning ratio of the $\theta$-graph with 7 cones is decreased from at most 7.5625 to at most 3.5132. These spanning proofs also imply improved upper bounds on the competitiveness of the $\theta$-routing algorithm. In particular, we show that the $\theta$-routing algorithm is $(1+2\sin(\theta/2)/(\cos(\theta/2)-\sin(\theta/2)))$-competitive on $\theta$-graphs with $4k+4$ cones and that this ratio is tight. #R##N#Finally, we present improved lower bounds on the spanning ratio of these graphs. Using these bounds, we provide a partial order on these families of $\theta$-graphs. In particular, we show that $\theta$-graphs with $4k+4$ cones have spanning ratio at least $1+2\tan(\theta/2)+2\tan^2(\theta/2)$. This is somewhat surprising since, for equal values of $k$, the spanning ratio of $\theta$-graphs with $4k+4$ cones is greater than that of $\theta$-graphs with $4k+2$ cones, showing that increasing the number of cones can make the spanning ratio worse.

Connected through hyperedge HE-1 (induced by source paper "expected complexity of routing in theta 6 and half theta 6 graphs"):
  with members:
    - "on the spanning and routing ratio of theta four"
    - "the θ 5 graph is a spanner"
    - "theta 3 is connected"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"

Connected through hyperedge HE-2 (induced by source paper "spanning properties of theta theta 6"):
  with members:
    - "on the spanning and routing ratio of theta four"
    - "odd yao yao graphs are not spanners"
    - "almost all even yao yao graphs are spanners"
    - "the θ 5 graph is a spanner"
    - "new and improved spanning ratios for yao graphs"
    - "an infinite class of sparse yao spanners"
    - "π 2 angle yao graphs are spanners"

Connected through hyperedge HE-3 (induced by source paper "routing on the visibility graph"):
  with members:
    - "constrained routing between non visible vertices"
    - "on plane constrained bounded degree spanners"
    - "upper bounds on the spanning ratio of constrained theta graphs"
    - "competitive local routing with constraints"

Connected through hyperedge HE-4 (induced by source paper "routing in polygonal domains"):
  with members:
    - "routing in unit disk graphs"
    - "routing on the visibility graph"
    - "constrained routing between non visible vertices"
    - "the θ 5 graph is a spanner"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"
    - "new routing techniques and their applications"
    - "competitive local routing with constraints"
    - "new and improved spanning ratios for yao graphs"

Connected through hyperedge HE-5 (induced by source paper "the price of order"):
  with members:
    - "the θ 5 graph is a spanner"
    - "theta 3 is connected"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"
    - "on the stretch factor of the theta 4 graph"

Connected through hyperedge HE-6 (induced by source paper "kinetic k semi yao graph and its applications"):
  with members:
    - "kinetic reverse k nearest neighbor problem"
    - "kinetic data structures for the semi yao graph and all nearest neighbors in r d"
    - "a simple faster method for kinetic proximity problems"
    - "sharp bounds on davenport schinzel sequences of every order"
    - "orthogonal range searching on the ram revisited"
    - "reverse nearest neighbor queries in fixed dimension"

Connected through hyperedge HE-7 (induced by source paper "spanning properties of theta theta graphs"):
  with members:
    - "the θ 5 graph is a spanner"
    - "the yao graph y_5 is a spanner"
    - "new and improved spanning ratios for yao graphs"
    - "on the stretch factor of the theta 4 graph"
    - "an infinite class of sparse yao spanners"
    - "π 2 angle yao graphs are spanners"

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)