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: "reduction of cascading outage risk based on risk gradient and markovian tree search"
  Abstract: Since cascading outages are major threats to power system operations, it is of great significance to reduce the risk of potential cascading outages. In this paper, a method for reduction of cascading outage risk based on Markovian tree (MT) search is proposed. Based on the MT expansion of the cascading outage risk, the risk gradient is computed with a forward-backward tree search scheme. The computation of risk gradient is incorporated into the procedure of risk assessment based on MT search, which is efficient with good convergence. Then the an optimization model for risk reduction (RR) is formulated by using risk gradient, which minimizes the cost of control while effectively reduces the cascading outage risk. Moreover, to overcome the limitation of linearization, an iterative risk reduction (IRR) algorithm is further developed. Test results on a 4-bus test system and the RTS-96 3-area test system verify the accuracy of risk gradient computation and effectiveness of the RR. And the performance of the IRR is demonstrated on RTS-96 3-area system and a 410-bus US-Canada northeast system model. The results show that the subsequent cascade risk and the total risk are reduced by 93.6% and 54.5%, respectively.

Connected through hyperedge HE-1 (induced by source paper "towards simulation and risk assessment of weather related cascading outages"):
  with members:
    - "efficient simulation of temperature evolution of overhead transmission lines based on analytical solution and nwp"
    - "risk assessment of multi timescale cascading outages based on markovian tree search"

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)