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 graphs of planar soap bubbles"
  Abstract: We characterize the graphs formed by two-dimensional soap bubbles as being exactly the 3-regular bridgeless planar multigraphs. Our characterization combines a local characterization of soap bubble graphs in terms of the curvatures of arcs meeting at common vertices, a proof that this characterization remains invariant under Moebius transformations, an application of Moebius invariance to prove bridgelessness, and a Moebius-invariant power diagram of circles previously developed by the author for its applications in graph drawing.

Connected through hyperedge HE-1 (induced by source paper "the galois complexity of graph drawing why numerical solutions are ubiquitous for force directed spectral and circle packing drawings"):
  with members:
    - "strict confluent drawing"
    - "a note on the unsolvability of the weighted region shortest path problem"
    - "planar lombardi drawings for subcubic graphs"
    - "optimal moebius transformations for information visualization and meshing"

Connected through hyperedge HE-2 (induced by source paper "diamond kite adaptive quadrilateral meshing"):
  with members:
    - "planar lombardi drawings for subcubic graphs"
    - "well centered triangulation"
    - "algorithms for coloring quadtrees"
    - "quadrilateral meshing by circle packing"
    - "optimal point placement for mesh smoothing"

Connected through hyperedge HE-3 (induced by source paper "drawing trees with perfect angular resolution and polynomial area"):
  with members:
    - "planar and poly arc lombardi drawings"
    - "planar lombardi drawings for subcubic graphs"
    - "pinning balloons with perfect angles and optimal area"
    - "lombardi drawings of graphs"
    - "trees with convex faces and optimal angles"
    - "confluent drawings visualizing non planar diagrams in a planar way"

Connected through hyperedge HE-4 (induced by source paper "planar lombardi drawings for subcubic graphs"):
  with members:
    - "steinitz theorems for simple orthogonal polyhedra"
    - "drawing trees with perfect angular resolution and polynomial area"
    - "lombardi drawings of graphs"
    - "optimal moebius transformations for information visualization and meshing"

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)