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: "definition sets for the direct kinematics of parallel manipulators"
  Abstract: The aim of this paper is to characterize the uniqueness domains in the workspace of parallel manipulators, as well as their image in the joint space. The notion of aspect introduced for serial manipulators in [Borrel 86] is redefined for such parallel manipulators. Then, it is shown that it is possible to link several solutions to the direct kinematic problem without meeting a singularity, thus meaning that the aspects are not uniqueness domains. Additional surfaces are characterized in the workspace which yield new uniqueness domains. An octree model of spaces is used to compute the joint space, the workspace and all other newly defined sets. This study is illustrated all along the paper with a 3-RPR planar parallel manipulator.

Connected through hyperedge HE-1 (induced by source paper "non singular assembly mode changing trajectories in the workspace for the 3 rps parallel robot"):
  with members:
    - "uniqueness domains and non singular assembly mode changing trajectories"
    - "on the determination of cusp points of 3 rpr parallel manipulators"
    - "non singular assembly mode changing motions for 3 rpr parallel manipulators"

Connected through hyperedge HE-2 (induced by source paper "singular surfaces and cusps in symmetric planar 3 rpr manipulators"):
  with members:
    - "kinematic analysis of a class of analytic planar 3 rpr parallel manipulators"
    - "non singular assembly mode changing motions for 3 rpr parallel manipulators"
    - "degeneracy study of the forward kinematics of planar 3 rpr parallel manipulators"
    - "singular curves and cusp points in the joint space of 3 rpr parallel manipulators"
    - "workspace and assembly modes in fully parallel manipulators a descriptive study"

Connected through hyperedge HE-3 (induced by source paper "a study of the singularity locus in the joint space of planar parallel manipulators special focus on cusps and nodes"):
  with members:
    - "non singular assembly mode changing motions for 3 rpr parallel manipulators"
    - "an algorithm for computing cusp points in the joint space of 3 rpr parallel manipulators"
    - "singular curves and cusp points in the joint space of 3 rpr parallel manipulators"
    - "workspace and assembly modes in fully parallel manipulators a descriptive study"

Connected through hyperedge HE-4 (induced by source paper "uniqueness domains and non singular assembly mode changing trajectories"):
  with members:
    - "non singular assembly mode changing motions for 3 rpr parallel manipulators"

Connected through hyperedge HE-5 (induced by source paper "joint space and workspace analysis of a two dof closed chain manipulator"):
  with members:
    - "an interval analysis based study for the design and the comparison of 3 dof parallel kinematic machines"

Connected through hyperedge HE-6 (induced by source paper "non singular assembly mode changing motions for 3 rpr parallel manipulators"):
  with members:
    - "architecture optimization of a 3 dof translational parallel mechanism for machining applications the orthoglide"
    - "an algorithm for computing cusp points in the joint space of 3 rpr parallel manipulators"
    - "degeneracy study of the forward kinematics of planar 3 rpr parallel manipulators"
    - "singular curves and cusp points in the joint space of 3 rpr parallel manipulators"
    - "the kinematic analysis of a symmetrical three degree of freedom planar parallel manipulator"
    - "workspace and assembly modes in fully parallel manipulators a descriptive study"

Connected through hyperedge HE-7 (induced by source paper "singular curves in the joint space and cusp points of 3 rpr parallel manipulators"):
  with members:
    - "singular curves and cusp points in the joint space of 3 rpr parallel manipulators"
    - "a classification of 3r orthogonal manipulators by the topology of their workspace"
    - "workspace and assembly modes in fully parallel manipulators a descriptive study"

Connected through hyperedge HE-8 (induced by source paper "an interval analysis based study for the design and the comparison of 3 dof parallel kinematic machines"):
  with members:
    - "architecture optimization of a 3 dof translational parallel mechanism for machining applications the orthoglide"
    - "a comparative study of parallel kinematic architectures for machining applications"
    - "workspace analysis of the orthoglide using interval analysis"

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.RO(Robotics)