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: "new and improved spanning ratios for yao graphs"
  Abstract: For a set of points in the plane and a fixed integer $k > 0$, the Yao graph $Y_k$ partitions the space around each point into $k$ equiangular cones of angle $\theta=2\pi/k$, and connects each point to a nearest neighbor in each cone. It is known for all Yao graphs, with the sole exception of $Y_5$, whether or not they are geometric spanners. In this paper we close this gap by showing that for odd $k \geq 5$, the spanning ratio of $Y_k$ is at most $1/(1-2\sin(3\theta/8))$, which gives the first constant upper bound for $Y_5$, and is an improvement over the previous bound of $1/(1-2\sin(\theta/2))$ for odd $k \geq 7$. We further reduce the upper bound on the spanning ratio for $Y_5$ from $10.9$ to $2+\sqrt{3} \approx 3.74$, which falls slightly below the lower bound of $3.79$ established for the spanning ratio of $\Theta_5$ ($\Theta$-graphs differ from Yao graphs only in the way they select the closest neighbor in each cone). This is the first such separation between a Yao and $\Theta$-graph with the same number of cones. We also give a lower bound of $2.87$ on the spanning ratio of $Y_5$. Finally, we revisit the $Y_6$ graph, which plays a particularly important role as the transition between the graphs ($k > 6$) for which simple inductive proofs are known, and the graphs ($k \le 6$) whose best spanning ratios have been established by complex arguments. Here we reduce the known spanning ratio of $Y_6$ from $17.6$ to $5.8$, getting closer to the spanning ratio of 2 established for $\Theta_6$.

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"
    - "upper bounds on the spanning ratio of constrained theta graphs"

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"
    - "towards tight bounds on theta 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 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"
    - "towards tight bounds on theta graphs"
    - "optimal local routing on delaunay triangulations defined by empty equilateral triangles"
    - "new routing techniques and their applications"
    - "competitive local routing with constraints"

Connected through hyperedge HE-4 (induced by source paper "almost all even yao yao graphs are spanners"):
  with members:
    - "an infinite class of sparse yao spanners"
    - "π 2 angle yao graphs are spanners"
    - "a simple yao yao based spanner of bounded degree"
    - "on the stretch factor of convex delaunay graphs"

Connected through hyperedge HE-5 (induced by source paper "the θ 5 graph is a spanner"):
  with members:
    - "on the average number of edges in theta graphs"
    - "on the stretch factor of the theta 4 graph"
    - "π 2 angle yao graphs are spanners"

Connected through hyperedge HE-6 (induced by source paper "spanning properties of theta theta graphs"):
  with members:
    - "the θ 5 graph is a spanner"
    - "towards tight bounds on theta graphs"
    - "the yao graph y_5 is a spanner"
    - "on the stretch factor of the theta 4 graph"
    - "an infinite class of sparse yao spanners"
    - "π 2 angle yao graphs are spanners"

Connected through hyperedge HE-7 (induced by source paper "optimal local routing on delaunay triangulations defined by empty equilateral triangles"):
  with members:
    - "succinct greedy geometric routing in the euclidean plane"

Connected through hyperedge HE-8 (induced by source paper "the yao graph y_5 is a spanner"):
  with members:
    - "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)