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: "upper bounds on the spanning ratio of constrained theta graphs"
  Abstract: We present tight upper and lower bounds on the spanning ratio of a large family of constrained $\theta$-graphs. We show that constrained $\theta$-graphs with $4k + 2$ ($k \geq 1$ and integer) cones have a tight spanning ratio of $1 + 2 \sin(\theta/2)$, where $\theta$ is $2 \pi / (4k + 2)$. We also present improved upper bounds on the spanning ratio of the other families of constrained $\theta$-graphs.

Connected through hyperedge HE-1 (induced by source paper "truly optimal euclidean spanners"):
  with members:
    - "on the spanning and routing ratio of theta four"
    - "odd yao yao graphs are not spanners"
    - "greedy spanners are optimal in doubling metrics"
    - "minor free graphs have light spanners"
    - "the greedy spanner is existentially optimal"
    - "almost all even yao yao graphs are spanners"
    - "a light metric spanner"
    - "new and improved spanning ratios for yao graphs"

Connected through hyperedge HE-2 (induced by source paper "routing on the visibility graph"):
  with members:
    - "constrained routing between non visible vertices"
    - "on plane constrained bounded degree spanners"
    - "towards tight bounds on theta graphs"
    - "competitive local routing with constraints"

Connected through hyperedge HE-3 (induced by source paper "constrained routing between non visible vertices"):
  with members:
    - "on plane constrained bounded degree spanners"
    - "competitive local routing with constraints"

Connected through hyperedge HE-4 (induced by source paper "on plane constrained bounded degree spanners"):
  with members:
    - "constrained generalized delaunay graphs are plane spanners"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"

Connected through hyperedge HE-5 (induced by source paper "competitive local routing with constraints"):
  with members:
    - "on plane constrained bounded degree spanners"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"

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)