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: "on the obfuscation complexity of planar graphs"
  Abstract: Being motivated by John Tantalo's Planarity Game, we consider straight line plane drawings of a planar graph $G$ with edge crossings and wonder how obfuscated such drawings can be. We define $obf(G)$, the obfuscation complexity of $G$, to be the maximum number of edge crossings in a drawing of $G$. Relating $obf(G)$ to the distribution of vertex degrees in $G$, we show an efficient way of constructing a drawing of $G$ with at least $obf(G)/3$ edge crossings. We prove bounds $(\delta(G)^2/24-o(1))n^2 < \obf G <3 n^2$ for an $n$-vertex planar graph $G$ with minimum vertex degree $\delta(G)\ge 2$. #R##N#The shift complexity of $G$, denoted by $shift(G)$, is the minimum number of vertex shifts sufficient to eliminate all edge crossings in an arbitrarily obfuscated drawing of $G$ (after shifting a vertex, all incident edges are supposed to be redrawn correspondingly). If $\delta(G)\ge 3$, then $shift(G)$ is linear in the number of vertices due to the known fact that the matching number of $G$ is linear. However, in the case $\delta(G)\ge2$ we notice that $shift(G)$ can be linear even if the matching number is bounded. As for computational complexity, we show that, given a drawing $D$ of a planar graph, it is NP-hard to find an optimum sequence of shifts making $D$ crossing-free.

Connected through hyperedge HE-1 (induced by source paper "geometry and generation of a new graph planarity game"):
  with members:
    - "untangling a planar graph"
    - "a polynomial bound for untangling geometric planar graphs"
    - "minimum weight triangulation is np hard"
    - "moving vertices to make drawings plane"

Connected through hyperedge HE-2 (induced by source paper "drawing arrangement graphs in small grids or how to play planarity"):
  with members:
    - "superpatterns and universal point sets"
    - "universal point sets for planar three tree"
    - "untangling polygons and graphs"
    - "untangling a planar graph"
    - "a polynomial bound for untangling geometric planar graphs"
    - "algorithms for drawing media"

Connected through hyperedge HE-3 (induced by source paper "untangling planar graphs from a specified vertex position hard cases"):
  with members:
    - "untangling polygons and graphs"
    - "untangling a planar graph"
    - "a polynomial bound for untangling geometric planar graphs"
    - "on collinear sets in straight line drawings"
    - "moving vertices to make drawings plane"

Connected through hyperedge HE-4 (induced by source paper "untangling polygons and graphs"):
  with members:
    - "untangling a planar graph"
    - "a polynomial bound for untangling geometric planar graphs"
    - "on collinear sets in straight line drawings"
    - "moving vertices to make drawings plane"

Connected through hyperedge HE-5 (induced by source paper "untangling a planar graph"):
  with members:
    - "untangling polygons and graphs"
    - "a polynomial bound for untangling geometric planar graphs"
    - "moving vertices to make drawings plane"
    - "the problem of compatible representatives"

Connected through hyperedge HE-6 (induced by source paper "a polynomial bound for untangling geometric planar graphs"):
  with members:
    - "untangling polygons and graphs"
    - "on collinear sets in straight line drawings"
    - "moving vertices to make drawings plane"

Connected through hyperedge HE-7 (induced by source paper "on collinear sets in straight line drawings"):
  with members:
    - "untangling planar graphs from a specified vertex position hard cases"
    - "untangling polygons and graphs"
    - "untangling a planar graph"
    - "a polynomial bound for untangling geometric planar graphs"

Connected through hyperedge HE-8 (induced by source paper "moving vertices to make drawings plane"):
  with members:
    - "untangling a planar graph"
    - "the problem of compatible representatives"

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.DM(Discrete Mathematics)