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: "algorithms for perfectly contractile graphs"
  Abstract: We consider the class ${\cal A}$ of graphs that contain no odd hole, no antihole of length at least $5$, and no prism (a graph consisting of two disjoint triangles with three disjoint paths between them) and the class ${\cal A}'$ of graphs that contain no odd hole, no antihole of length at least $5$, and no odd prism (prism whose three paths are odd). These two classes were introduced by Everett and Reed and are relevant to the study of perfect graphs. We give polynomial-time recognition algorithms for these two classes. In contrast we prove that determining if a general graph contains a prism (or an even prism, or an odd prism) is NP-complete.

Connected through hyperedge HE-1 (induced by source paper "three in a tree in near linear time"):
  with members:
    - "graph pattern detection hardness for all induced patterns and faster non induced cycles"
    - "a faster algorithm to recognize even hole free graphs"
    - "on the structure of pan even hole free graphs"
    - "powers of tensors and fast matrix multiplication"
    - "detecting an induced net subdivision"
    - "large induced subgraphs via triangulations and cmso"
    - "induced disjoint paths in claw free graphs"
    - "detecting 2 joins faster"

Connected through hyperedge HE-2 (induced by source paper "a faster algorithm to recognize even hole free graphs"):
  with members:
    - "detecting 2 joins faster"
    - "combinatorial optimization with 2 joins"

Connected through hyperedge HE-3 (induced by source paper "claw free t perfect graphs can be recognised in polynomial time"):
  with members:
    - "induced disjoint paths in claw free graphs"

Connected through hyperedge HE-4 (induced by source paper "graphs that do not contain a cycle with a node that has at least two neighbors on it"):
  with members:
    - "edge colouring and total colouring chordless graphs"
    - "detecting induced subgraphs"

Connected through hyperedge HE-5 (induced by source paper "detecting induced subgraphs"):
  with members:
    - "algorithms for square 3pc cdot cdot free berge 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)