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: "volatility of power grids under real time pricing"
  Abstract: The paper proposes a framework for modeling and analysis of the dynamics of supply, demand, and clearing prices in power system with real-time retail pricing and information asymmetry. Real-time retail pricing is characterized by passing on the real-time wholesale electricity prices to the end consumers, and is shown to create a closed-loop feedback system between the physical layer and the market layer of the power system. In the absence of a carefully designed control law, such direct feedback between the two layers could increase volatility and lower the system's robustness to uncertainty in demand and generation. A new notion of generalized price-elasticity is introduced, and it is shown that price volatility can be characterized in terms of the system's maximal relative price elasticity, defined as the maximal ratio of the generalized price-elasticity of consumers to that of the producers. As this ratio increases, the system becomes more volatile, and eventually, unstable. As new demand response technologies and distributed storage increase the price-elasticity of demand, the architecture under examination is likely to lead to increased volatility and possibly instability. This highlights the need for assessing architecture systematically and in advance, in order to optimally strike the trade-offs between volatility, economic efficiency, and system reliability.

Connected through hyperedge HE-1 (induced by source paper "incentive mechanisms to prevent efficiency loss of non profit utilities"):
  with members:
    - "stability analysis of wholesale electricity markets under dynamic consumption models and real time pricing"
    - "incentives based mechanism for efficient demand response programs"

Connected through hyperedge HE-2 (induced by source paper "a dynamical systems approach to modeling and analysis of transactive energy coordination"):
  with members:
    - "load synchronization and sustained oscillations induced by transactive control"

Connected through hyperedge HE-3 (induced by source paper "implementing flexible demand real time price vs market integration"):
  with members:
    - "agent based model for spot and balancing electricity markets"
    - "models for the modern power grid"

Connected through hyperedge HE-4 (induced by source paper "resilience of locally routed network flows more capacity is not always better"):
  with members:
    - "informational braess paradox the effect of information on traffic congestion"
    - "formation of robust multi agent networks through self organizing random regular graphs"
    - "robust network routing under cascading failures"

Connected through hyperedge HE-5 (induced by source paper "resilient operation of transportation networks via variable speed limits"):
  with members:
    - "resilience of locally routed network flows more capacity is not always better"
    - "formation of robust multi agent networks through self organizing random regular graphs"

Connected through hyperedge HE-6 (induced by source paper "demand dispatch with heterogeneous intelligent loads"):
  with members:
    - "state estimation for the individual and the population in mean field control with application to demand dispatch"
    - "smart fridge dumb grid demand dispatch for the power grid of 2020"

Connected through hyperedge HE-7 (induced by source paper "stability analysis of wholesale electricity markets under dynamic consumption models and real time pricing"):
  with members:
    - "residential demand response targeting using machine learning with observational data"

Connected through hyperedge HE-8 (induced by source paper "real time power balancing via decentralized coordinated home energy scheduling"):
  with members:
    - "coordinated home energy management for real time power balancing"

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)