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: "the complexity of planar graph choosability"
  Abstract: A graph $G$ is {\em $k$-choosable} if for every assignment of a set $S(v)$ of $k$ colors to every vertex $v$ of $G$, there is a proper coloring of $G$ that assigns to each vertex $v$ a color from $S(v)$. We consider the complexity of deciding whether a given graph is $k$-choosable for some constant $k$. In particular, it is shown that deciding whether a given planar graph is 4-choosable is NP-hard, and so is the problem of deciding whether a given planar triangle-free graph is 3-choosable. We also obtain simple constructions of a planar graph which is not 4-choosable and a planar triangle-free graph which is not 3-choosable.

Connected through hyperedge HE-1 (induced by source paper "choosability with limited number of colors"):
  with members:
    - "some results on a b choosability"

Connected through hyperedge HE-2 (induced by source paper "filling the complexity gaps for colouring planar and bounded degree graphs"):
  with members:
    - "partitioning a triangle free planar graph into a forest and a forest of bounded degree"
    - "list coloring apex minor free graphs"
    - "a survey on the computational complexity of colouring graphs with forbidden subgraphs"
    - "list coloring embedded graphs"

Connected through hyperedge HE-3 (induced by source paper "a survey on the computational complexity of colouring graphs with forbidden subgraphs"):
  with members:
    - "bounding the clique width of h free chordal graphs"
    - "three coloring graphs with no induced seven vertex path ii using a triangle"
    - "the coloring problem for p 5 p 5 free graphs and p 5 k p e free graphs is polynomial"
    - "bounding clique width via perfect graphs"
    - "clique width of graph classes defined by two forbidden induced subgraphs"
    - "narrowing the complexity gap for colouring c_s p_t free graphs"
    - "4 coloring p_6 free graphs with no induced 5 cycles"
    - "polynomial time algorithms for minimum weighted colorings of p_5 bar p _5 free graphs and related graph classes"

Connected through hyperedge HE-4 (induced by source paper "list coloring apex minor free graphs"):
  with members:
    - "list coloring embedded graphs"

Connected through hyperedge HE-5 (induced by source paper "some results on a b choosability"):
  with members:
    - "choice numbers of 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.DM(Discrete Mathematics)