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: "fixed orientation equilateral triangle matching of point sets"
  Abstract: Given a point set $P$ and a class $\mathcal{C}$ of geometric objects, $G_\mathcal{C}(P)$ is a geometric graph with vertex set $P$ such that any two vertices $p$ and $q$ are adjacent if and only if there is some $C \in \mathcal{C}$ containing both $p$ and $q$ but no other points from $P$. We study $G_{\bigtriangledown}(P)$ graphs where $\bigtriangledown$ is the class of downward equilateral triangles (ie. equilateral triangles with one of their sides parallel to the x-axis and the corner opposite to this side below that side). For point sets in general position, these graphs have been shown to be equivalent to half-$\Theta_6$ graphs and TD-Delaunay graphs. #R##N#The main result in our paper is that for point sets $P$ in general position, $G_{\bigtriangledown}(P)$ always contains a matching of size at least $\lceil\frac{n-2}{3}\rceil$ and this bound cannot be improved above $\lceil\frac{n-1}{3}\rceil$. #R##N#We also give some structural properties of $G_{\davidsstar}(P)$ graphs, where $\davidsstar$ is the class which contains both upward and downward equilateral triangles. We show that for point sets in general position, the block cut point graph of $G_{\davidsstar}(P)$ is simply a path. Through the equivalence of $G_{\davidsstar}(P)$ graphs with $\Theta_6$ graphs, we also derive that any $\Theta_6$ graph can have at most $5n-11$ edges, for point sets in general position.

Connected through hyperedge HE-1 (induced by source paper "maximum matchings and minimum blocking sets in θ 6 graphs"):
  with members:
    - "spanning properties of theta theta 6"
    - "on the spanning and routing ratio of theta four"
    - "the θ 5 graph is a spanner"
    - "higher order triangular distance delaunay graphs graph theoretical properties"
    - "on the average number of edges in theta graphs"
    - "witness gabriel graphs"
    - "witness delaunay graphs"

Connected through hyperedge HE-2 (induced by source paper "matchings in geometric graphs"):
  with members:
    - "packing plane spanning trees and paths in complete geometric graphs"
    - "flip distance to a non crossing perfect matching"
    - "balanced partitions of 3 colored geometric sets in the plane"
    - "packing plane perfect matchings into a point set"
    - "10 gabriel graphs are hamiltonian"
    - "higher order triangular distance delaunay graphs graph theoretical properties"
    - "approximating the bottleneck plane perfect matching of a point set"
    - "bottleneck non crossing matching in the plane"

Connected through hyperedge HE-3 (induced by source paper "strong matching of points with geometric shapes"):
  with members:
    - "matching in gabriel graphs"
    - "higher order triangular distance delaunay graphs graph theoretical properties"
    - "on the stretch factor of convex delaunay graphs"

Connected through hyperedge HE-4 (induced by source paper "higher order triangular distance delaunay graphs graph theoretical properties"):
  with members:
    - "10 gabriel graphs are hamiltonian"
    - "witness gabriel graphs"
    - "on the stretch factor of convex delaunay graphs"

Connected through hyperedge HE-5 (induced by source paper "matching in gabriel graphs"):
  with members:
    - "higher order triangular distance delaunay graphs graph theoretical properties"
    - "witness gabriel graphs"

Connected through hyperedge HE-6 (induced by source paper "selection lemmas for various geometric objects"):
  with members:
    - "small strong epsilon nets"

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)