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: "trajectory optimization through contacts and automatic gait discovery for quadrupeds"
  Abstract: In this work we present a trajectory Optimization framework for whole-body motion planning through contacts. We demonstrate how the proposed approach can be applied to automatically discover different gaits and dynamic motions on a quadruped robot. In contrast to most previous methods, we do not pre-specify contact switches, timings, points or gait patterns, but they are a direct outcome of the optimization. Furthermore, we optimize over the entire dynamics of the robot, which enables the optimizer to fully leverage the capabilities of the robot. To illustrate the spectrum of achievable motions, here we show eight different tasks, which would require very different control structures when solved with state-of-the-art methods. Using our trajectory Optimization approach, we are solving each task with a simple, high level cost function and without any changes in the control structure. Furthermore, we fully integrated our approach with the robot's control and estimation framework such that optimization can be run online. By demonstrating a rough manipulation task with multiple dynamic contact switches, we exemplarily show how optimized trajectories and control inputs can be directly applied to hardware.

Connected through hyperedge HE-1 (induced by source paper "learning how to walk warm starting optimal control solver with memory of motion"):
  with members:
    - "memory of motion for warm starting trajectory optimization"
    - "crocoddyl an efficient and versatile framework for multi contact optimal control"
    - "passive whole body control for quadruped robots experimental validation over challenging terrain"
    - "differential dynamic programming for multi phase rigid contact dynamics"
    - "simultaneous contact gait and motion planning for robust multi legged locomotion via mixed integer convex optimization"
    - "planning and execution of dynamic whole body locomotion for a hydraulic quadruped on challenging terrain"

Connected through hyperedge HE-2 (induced by source paper "learning agile and dynamic motor skills for legged robots"):
  with members:
    - "learning symmetric and low energy locomotion"
    - "sim to real transfer of robotic control with dynamics randomization"
    - "sim to real learning agile locomotion for quadruped robots"
    - "feedback control for cassie with deep reinforcement learning"
    - "control of a quadrotor with reinforcement learning"
    - "fast trajectory optimization for legged robots using vertex based zmp constraints"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"
    - "learning locomotion skills using deeprl does the choice of action space matter"

Connected through hyperedge HE-3 (induced by source paper "crocoddyl an efficient and versatile framework for multi contact optimal control"):
  with members:
    - "differential dynamic programming for multi phase rigid contact dynamics"
    - "whole body nonlinear model predictive control through contacts for quadrupeds"
    - "simultaneous contact gait and motion planning for robust multi legged locomotion via mixed integer convex optimization"
    - "motion planning for quadrupedal locomotion coupled planning terrain mapping and whole body control"
    - "a family of iterative gauss newton shooting methods for nonlinear optimal control"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"
    - "balancing experiments on a torque controlled humanoid with hierarchical inverse dynamics"

Connected through hyperedge HE-4 (induced by source paper "frequency aware model predictive control"):
  with members:
    - "exploiting the natural dynamics of series elastic robots by actuator centered sequential linear programming"
    - "real time motion planning of legged robots a model predictive control approach"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"

Connected through hyperedge HE-5 (induced by source paper "whole body nonlinear model predictive control through contacts for quadrupeds"):
  with members:
    - "the control toolbox an open source c library for robotics optimal and model predictive control"
    - "a family of iterative gauss newton shooting methods for nonlinear optimal control"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"
    - "automatic differentiation of rigid body dynamics for optimal control and estimation"
    - "hierarchical planning of dynamic movements without scheduled contact sequences"
    - "projection based whole body motion planning for legged robots"
    - "planning and execution of dynamic whole body locomotion for a hydraulic quadruped on challenging terrain"
    - "trajectory generation for multi contact momentum control"

Connected through hyperedge HE-6 (induced by source paper "the control toolbox an open source c library for robotics optimal and model predictive control"):
  with members:
    - "whole body nonlinear model predictive control through contacts for quadrupeds"
    - "a family of iterative gauss newton shooting methods for nonlinear optimal control"
    - "efficient kinematic planning for mobile manipulators with non holonomic constraints using optimal control"
    - "blasfeo basic linear algebra subroutines for embedded optimization"
    - "automatic differentiation of rigid body dynamics for optimal control and estimation"
    - "odeint solving ordinary differential equations in c"

Connected through hyperedge HE-7 (induced by source paper "contact implicit trajectory optimization based on a variable smooth contact model and successive convexification"):
  with members:
    - "a comparative analysis of contact models in trajectory optimization for manipulation"
    - "whole body nonlinear model predictive control through contacts for quadrupeds"
    - "a family of iterative gauss newton shooting methods for nonlinear optimal control"
    - "automatic differentiation of rigid body dynamics for optimal control and estimation"
    - "hierarchical planning of dynamic movements without scheduled contact sequences"

Connected through hyperedge HE-8 (induced by source paper "contact implicit optimization of locomotion trajectories for a quadrupedal microrobot"):
  with members:
    - "fast trajectory optimization for legged robots using vertex based zmp constraints"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"
    - "planning and execution of dynamic whole body locomotion for a hydraulic quadruped on challenging terrain"

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)