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: "partitioning a triangle free planar graph into a forest and a forest of bounded degree"
  Abstract: An $({\cal F},{\cal F}_d)$-partition of a graph is a vertex-partition into two sets $F$ and $F_d$ such that the graph induced by $F$ is a forest and the one induced by $F_d$ is a forest with maximum degree at most $d$. We prove that every triangle-free planar graph admits an $({\cal F},{\cal F}_5)$-partition. Moreover we show that if for some integer $d$ there exists a triangle-free planar graph that does not admit an $({\cal F},{\cal F}_d)$-partition, then it is an NP-complete problem to decide whether a triangle-free planar graph admits such a partition.

Connected through hyperedge HE-1 (induced by source paper "recognizing graphs close to bipartite graphs with an application to colouring reconfiguration"):
  with members:
    - "independent feedback vertex sets for graphs of bounded diameter"
    - "independent feedback vertex set for p_5 free graphs"
    - "recognition of unipolar and generalised split graphs"
    - "finding shortest paths between graph colourings"
    - "brooks vertex colouring theorem in linear time"

Connected through hyperedge HE-2 (induced by source paper "independent feedback vertex sets for graphs of bounded diameter"):
  with members:
    - "independent feedback vertex set for p_5 free graphs"
    - "the complexity of surjective homomorphism problems a survey"

Connected through hyperedge HE-3 (induced by source paper "filling the complexity gaps for colouring planar and bounded degree graphs"):
  with members:
    - "list coloring apex minor free graphs"
    - "a survey on the computational complexity of colouring graphs with forbidden subgraphs"
    - "list coloring embedded graphs"
    - "the complexity of planar graph choosability"

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)