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: "weighted efficient domination in classes of p 6 free graphs"
  Abstract: In a graph $G$, an efficient dominating set is a subset $D$ of vertices such that $D$ is an independent set and each vertex outside $D$ has exactly one neighbor in $D$. The Minimum Weight Efficient Dominating Set (Min-WED) problem asks for an efficient dominating set of total minimum weight in a given vertex-weighted graph; the Maximum Weight Efficient Dominating Set (Max-WED) problem is defined similarly. The Min-WED/Max-WED is known to be $NP$-complete for $P_7$-free graphs, and is known to be polynomial time solvable for $P_5$-free graphs. However, the computational complexity of the Min-WED/Max-WED problem is unknown for $P_6$-free graphs. In this paper, we show that the Min-WED/Max-WED problem can be solved in polynomial time for two subclasses of $P_6$-free graphs, namely for ($P_6,S_{1,1,3}$)-free graphs, and for ($P_6$, bull)-free graphs.

Connected through hyperedge HE-1 (induced by source paper "efficient domination for some subclasses of p_6 free graphs in polynomial time"):
  with members:
    - "polynomial time algorithms for weighted efficient domination problems in at free graphs and dually chordal graphs"
    - "weighted efficient domination for p_5 kp_2 free graphs in polynomial time"
    - "new polynomial cases of the weighted efficient domination problem"
    - "efficient dominating and edge dominating sets for graphs and hypergraphs"

Connected through hyperedge HE-2 (induced by source paper "maximum weight independent sets for p_7 triangle free graphs in polynomial time"):
  with members:
    - "an cal o n 2 log n algorithm for the weighted stable set problem in claw free graphs"
    - "independence and efficient domination on p_6 free graphs"
    - "weighted independent sets in a subclass of p_6 free 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)