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: "stability of surface contacts for humanoid robots closed form formulae of the contact wrench cone for rectangular support areas"
  Abstract: Humanoid robots locomote by making and breaking contacts with their environment. A crucial problem is therefore to find precise criteria for a given contact to remain stable or to break. For rigid surface contacts, the most general criterion is the Contact Wrench Condition (CWC). To check whether a motion satisfies the CWC, existing approaches take into account a large number of individual contact forces (for instance, one at each vertex of the support polygon), which is computationally costly and prevents the use of efficient inverse-dynamics methods. Here we argue that the CWC can be explicitly computed without reference to individual contact forces, and give closed-form formulae in the case of rectangular surfaces -- which is of practical importance. It turns out that these formulae simply and naturally express three conditions: (i) Coulomb friction on the resultant force, (ii) ZMP inside the support area, and (iii) bounds on the yaw torque. Conditions (i) and (ii) are already known, but condition (iii) is, to the best of our knowledge, novel. It is also of particular interest for biped locomotion, where undesired foot yaw rotations are a known issue. We also show that our formulae yield simpler and faster computations than existing approaches for humanoid motions in single support, and demonstrate their consistency in the OpenHRP simulator.

Connected through hyperedge HE-1 (induced by source paper "highly dynamic quadruped locomotion via whole body impulse control and model predictive control"):
  with members:
    - "frequency aware model predictive control"
    - "dynamic locomotion for passive ankle biped robots and humanoids using whole body locomotion control"
    - "learning agile and dynamic motor skills for legged robots"
    - "whole body nonlinear model predictive control through contacts for quadrupeds"

Connected through hyperedge HE-2 (induced by source paper "efficient trajectory generation for robotic systems constrained by contact forces"):
  with members:
    - "trajectory generation for robotic systems with contact force constraints"
    - "simulation based reachability analysis for nonlinear systems using componentwise contraction properties"

Connected through hyperedge HE-3 (induced by source paper "formal connections between template and anchor models via approximate simulation"):
  with members:
    - "multi contact walking pattern generation based on model preview control of 3d com accelerations"
    - "balancing experiments on a torque controlled humanoid with hierarchical inverse dynamics"

Connected through hyperedge HE-4 (induced by source paper "critically fast pick and place with suction cups"):
  with members:
    - "a new approach to time optimal path parameterization based on reachability analysis"
    - "cartman the low cost cartesian manipulator that won the amazon robotics challenge"
    - "analysis and observations from the first amazon picking challenge"
    - "a general fast and robust implementation of the time optimal path parameterization algorithm"

Connected through hyperedge HE-5 (induced by source paper "trajectory generation for robotic systems with contact force constraints"):
  with members:
    - "simulation based reachability analysis for nonlinear systems using componentwise contraction properties"

Connected through hyperedge HE-6 (induced by source paper "on time optimisation of centroidal momentum dynamics"):
  with members:
    - "simultaneous contact gait and motion planning for robust multi legged locomotion via mixed integer convex optimization"
    - "an efficient optimal planning and control framework for quadrupedal locomotion"
    - "when to make a step tackling the timing problem in multi contact locomotion by topp mpc"
    - "momentum control with hierarchical inverse dynamics on a torque controlled humanoid"
    - "structured contact force optimization for kino dynamic motion generation"
    - "multi contact walking pattern generation based on model preview control of 3d com accelerations"
    - "trajectory generation for multi contact momentum control"

Connected through hyperedge HE-7 (induced by source paper "dynamic walking over rough terrains by nonlinear predictive control of the floating base inverted pendulum"):
  with members:
    - "when to make a step tackling the timing problem in multi contact locomotion by topp mpc"
    - "step timing adjustment a step toward generating robust gaits"
    - "multi contact walking pattern generation based on model preview control of 3d com accelerations"
    - "zmp support areas for multi contact mobility under frictional constraints"
    - "a general fast and robust implementation of the time optimal path parameterization algorithm"

Connected through hyperedge HE-8 (induced by source paper "when to make a step tackling the timing problem in multi contact locomotion by topp mpc"):
  with members:
    - "walking stabilization using step timing and location adjustment on the humanoid robot atlas"
    - "on the structure of the time optimal path parameterization problem with third order constraints"
    - "step timing adjustment a step toward generating robust gaits"
    - "multi contact walking pattern generation based on model preview control of 3d com accelerations"
    - "trajectory generation for multi contact momentum control"
    - "zmp support areas for multi contact mobility under frictional constraints"
    - "a general fast and robust implementation of the time optimal path parameterization algorithm"

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)