human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "graphical models and belief propagation hierarchy for physics constrained network flows"):
  Abstract: We review new ideas and the first results from the application of the graphical models approach, which originated from statistical physics, information theory, computer science, and machine learning, to optimization problems of network flow type with additional constraints related to the physics of the flow. We illustrate the general concepts on a number of enabling examples from power system and natural gas transmission (continental scale) and distribution (district scale) systems.

Includes members:
  Member "how to calculate partition functions using convex programming hierarchies provable bounds for variational methods":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "gauges loops and polynomials for partition functions of graphical models")
  Member "minimum weight perfect matching via blossom belief propagation":
    also connected through other hyperedges:
      (none)
  Member "a differential analysis of the power flow equations":
    also connected through other hyperedges:
      (none)
  Member "solving the power flow equations a monotone operator approach":
    also connected through other hyperedges:
      (none)
  Member "submodular functions from discrete to continous domains":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "black box submodular maximization discrete and continuous settings")
  Member "natural gas flow solutions with guarantees a monotone operator theory approach":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "solvability of power flow equations through existence and uniqueness of complex fixed point")
  Member "optimal compression in natural gas networks a geometric programming approach":
    also connected through other hyperedges:
      (none)
  Member "the power of linear programming for general valued csps":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "on planar valued csps")

Question: Please tell me which class the source paper 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)