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: "flip distance between triangulations of a simple polygon is np complete"
  Abstract: Let T be a triangulation of a simple polygon. A flip in T is the operation of replacing one diagonal of T by a different one such that the resulting graph is again a triangulation. The flip distance between two triangulations is the smallest number of flips required to transform one triangulation into the other. For the special case of convex polygons, the problem of determining the shortest flip distance between two triangulations is equivalent to determining the rotation distance between two binary trees, a central problem which is still open after over 25 years of intensive study. We show that computing the flip distance between two triangulations of a simple polygon is NP-hard. This complements a recent result that shows APX-hardness of determining the flip distance between two triangulations of a planar point set.

Connected through hyperedge HE-1 (induced by source paper "shortest reconfiguration of perfect matchings via alternating cycles"):
  with members:
    - "the perfect matching reconfiguration problem"
    - "shortest reconfiguration of matchings"
    - "the time complexity of permutation routing via matching token swapping and a variant"
    - "shortest reconfiguration of sliding tokens on a caterpillar"
    - "flip distance between triangulations of a planar point set is apx hard"
    - "finding shortest paths between graph colourings"
    - "shortest reconfiguration paths in the solution space of boolean formulas"
    - "the complexity of change"

Connected through hyperedge HE-2 (induced by source paper "flip distance to some plane configurations"):
  with members:
    - "flip distance to a non crossing perfect matching"
    - "bichromatic compatible matchings"
    - "a history of flips in combinatorial triangulations"

Connected through hyperedge HE-3 (induced by source paper "an improved fpt algorithm for the flip distance problem"):
  with members:
    - "flip distance between triangulations of a planar point set is apx hard"
    - "computing the flip distance between triangulations"

Connected through hyperedge HE-4 (induced by source paper "shortest reconfiguration of matchings"):
  with members:
    - "an improved fpt algorithm for the flip distance problem"
    - "solving the rubik s cube optimally is np complete"
    - "the complexity of independent set reconfiguration on bipartite graphs"
    - "a reconfigurations analogue of brooks theorem and its consequences"
    - "shortest reconfiguration of sliding tokens on a caterpillar"
    - "flip distance between triangulations of a planar point set is apx hard"
    - "recoloring graphs via tree decompositions"
    - "shortest reconfiguration paths in the solution space of boolean formulas"

Connected through hyperedge HE-5 (induced by source paper "a note on the flip distance problem for edge labeled triangulations"):
  with members:
    - "flip distance between triangulations of a planar point set is apx hard"
    - "flipping edge labelled triangulations"
    - "flip distance between two triangulations of a point set is np complete"

Connected through hyperedge HE-6 (induced by source paper "a proof of the orbit conjecture for flipping edge labelled triangulations"):
  with members:
    - "reconfiguring ordered bases of a matroid"
    - "flips in edge labelled pseudo triangulations"
    - "flip distance between triangulations of a planar point set is apx hard"
    - "computing the flip distance between triangulations"
    - "the complexity of change"
    - "flipping edge labelled triangulations"
    - "flip distance between two triangulations of a point set is np complete"
    - "happy endings for flip graphs"

Connected through hyperedge HE-7 (induced by source paper "planar 3 sat with a clause variable cycle"):
  with members:
    - "the complexity of drawing graphs on few lines and few planes"
    - "on planar variants of the monotone satisfiability problem with bounded variable appearances"
    - "classic nintendo games are computationally hard"
    - "minimum weight triangulation is np hard"
    - "the complexity of planar counting problems"
    - "the problem of compatible representatives"

Connected through hyperedge HE-8 (induced by source paper "flip distance to a non crossing perfect matching"):
  with members:
    - "point sets with many non crossing perfect matchings"
    - "quasi parallel segments and characterization of unique bichromatic matchings"
    - "bichromatic compatible matchings"

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)