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: "π 2 angle yao graphs are spanners"
  Abstract: We show that the Yao graph Y4 in the L2 metric is a spanner with stretch factor . Enroute to this, we also show that the Yao graph in the L∞ metric is a plane spanner with stretch factor 8.

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"
    - "new and improved spanning ratios for yao graphs"
    - "an infinite class of sparse yao 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:
    - "new and improved spanning ratios for yao graphs"
    - "an infinite class of sparse yao 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:
    - "new and improved spanning ratios for yao graphs"
    - "on the average number of edges in theta graphs"
    - "on the stretch factor of the theta 4 graph"

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"
    - "new and improved spanning ratios for yao graphs"
    - "on the stretch factor of the theta 4 graph"
    - "an infinite class of sparse yao spanners"

Connected through hyperedge HE-7 (induced by source paper "there are plane spanners of maximum degree 4"):
  with members:
    - "on plane constrained bounded degree spanners"
    - "the stretch factor of the delaunay triangulation is less than 1 998"
    - "on geometric spanners of euclidean and unit disk graphs"

Connected through hyperedge HE-8 (induced by source paper "the yao graph y_5 is a spanner"):
  with members:
    - "new and improved spanning ratios for yao 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)