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: "combinatorics and the rigidity of cad systems"
  Abstract: We study the rigidity of body-and-cad frameworks which capture the majority of the geometric constraints used in 3D mechanical engineering CAD software. We present a combinatorial characterization of the generic minimal rigidity of a subset of body-and-cad frameworks in which we treat 20 of the 21 body-and-cad constraints, omitting only point-point coincidences. While the handful of classical combinatorial characterizations of rigidity focus on distance constraints between points, this is the first result simultaneously addressing coincidence, angular, and distance constraints. Our result is stated in terms of the partitioning of a graph into edge-disjoint spanning trees. This combinatorial approach provides the theoretical basis for the development of deterministic algorithms (that will not depend on numerical methods) for analyzing the rigidity of body-and-cad frameworks.

Connected through hyperedge HE-1 (induced by source paper "combinatorial rigidity of incidence systems and application to dictionary learning"):
  with members:
    - "optimal decomposition and recombination of isostatic geometric constraint systems for designing layered materials"
    - "reduction of constraint systems"
    - "new algorithms for learning incoherent and overcomplete dictionaries"
    - "learning sparsely used overcomplete dictionaries via alternating minimization"
    - "the algebraic combinatorial approach for low rank matrix completion"
    - "generalized principal component analysis gpca"
    - "exact recovery of sparsely used dictionaries"
    - "body and cad geometric constraint systems"

Connected through hyperedge HE-2 (induced by source paper "tree decomposable and underconstrained geometric constraint problems"):
  with members:
    - "cayley configuration spaces of 1 dof tree decomposable linkages part ii combinatorial characterization of complexity"
    - "cayley configuration spaces of 2d mechanisms part i extreme points continuous motion paths and minimal representations"

Connected through hyperedge HE-3 (induced by source paper "an incidence geometry approach to dictionary learning"):
  with members:
    - "new algorithms for learning incoherent and overcomplete dictionaries"
    - "learning sparsely used overcomplete dictionaries via alternating minimization"
    - "generalized principal component analysis gpca"
    - "exact recovery of sparsely used dictionaries"
    - "body and cad geometric constraint systems"
    - "on affine rigidity"

Connected through hyperedge HE-4 (induced by source paper "algorithms for detecting dependencies and rigid subsystems for cad"):
  with members:
    - "nucleation free 3d rigidity"
    - "rigid components in fixed lattice and cone frameworks"
    - "body and cad geometric constraint systems"

Connected through hyperedge HE-5 (induced by source paper "special positions of body and cad frameworks"):
  with members:
    - "rigid components in fixed lattice and cone frameworks"
    - "body and cad geometric constraint systems"

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)