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: "structure theory for ensemble controllability observability and duality"
  Abstract: Ensemble control deals with the problem of how to use finitely many control inputs to simultaneously steer a large population (in the limit, a continuum) of control systems. Dual to the ensemble control problem, ensemble estimation deals with the problem of using finitely many measurement outputs to estimate the initial condition of every system in the ensemble. We introduce in the paper an innovative class of ensemble systems, termed distinguished ensemble system, and establish sufficient conditions for controllability and observability of such system. A distinguished ensemble system is comprised of two key components, namely distinguished control vector fields and codistinguished observation functions. Roughly speaking, a set of vector fields is distinguished if they are closed (up to scaling) under Lie bracket, and moreover, every vector field in the set can be generated (up to scaling) by a Lie bracket of two vector fields in the same set. Similarly, a set of functions is codistinguished with respect to a set of vector fields if the directional derivatives of the functions along the given vector fields yield (up to scaling) the same set of functions. We further address in the paper the existence of a distinguished ensemble system over Lie groups and their homogeneous spaces. Specifically, we show that every connected, semi-simple Lie group admits a set of distinguished vector fields, together with a set of codistinguished functions. The proof is constructive, leveraging the structure theory for semi-simple real Lie algebras. Various examples will be introduced along the presentation illustrating the key definitions and the main results.

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.SY(Systems and Control)