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: "complex demand knapsack problems and incentives in ac power systems"
  Abstract: We consider AC electrical systems where each electrical device has a power demand expressed as a complex number, and there is a limit on the magnitude of total power supply. Motivated by this scenario, we introduce the complex-demand knapsack problem (C-KP), a new variation of the traditional knapsack problem, where each item is associated with a demand as a complex number, rather than a real number often interpreted as weight or size of the item. While keeping the same goal as to maximize the sum of values of the selected items, we put the capacity limit on the magnitude of the sum of satisfied demands. For C-KP, we prove its inapproximability by FPTAS (unless P = NP), as well as presenting a (1/2-epsilon)-approximation algorithm. Furthermore, we investigate the selfish multi-agent setting where each agent is in charge of one item, and an agent may misreport the demand and value of his item for his own interest. We show a simple way to adapt our approximation algorithm to be monotone, which is sufficient for the existence of incentive compatible payments such that no agent has an incentive to misreport. Our results shed insight on the design of multi-agent systems for smart grid.

Connected through hyperedge HE-1 (induced by source paper "combinatorial optimization of ac optimal power flow with discrete demands in radial networks"):
  with members:
    - "optimal power flow with inelastic demands for demand response in radial distribution networks"
    - "truthful mechanisms for combinatorial allocation of electric power in alternating current electric systems for smart grid"

Connected through hyperedge HE-2 (induced by source paper "complex demand scheduling problem with application in smart grid"):
  with members:
    - "combinatorial optimization of ac optimal power flow with discrete demands in radial networks"
    - "optimal power flow with inelastic demands for demand response in radial distribution networks"
    - "truthful mechanisms for combinatorial allocation of electric power in alternating current electric systems for smart grid"
    - "online algorithm for demand response with inelastic demands and apparent power constraint"
    - "truthful mechanisms for combinatorial ac electric power allocation"
    - "a mazing 2 eps approximation for unsplittable flow on a path"
    - "vector bin packing with multiple choice"

Connected through hyperedge HE-3 (induced by source paper "optimal power flow with inelastic demands for demand response in radial distribution networks"):
  with members:
    - "truthful mechanisms for combinatorial allocation of electric power in alternating current electric systems for smart grid"
    - "ac feasibility on tree networks is np hard"
    - "truthful mechanisms for combinatorial ac electric power allocation"

Connected through hyperedge HE-4 (induced by source paper "online algorithm for demand response with inelastic demands and apparent power constraint"):
  with members:
    - "optimal power flow with inelastic demands for demand response in radial distribution networks"
    - "truthful mechanisms for combinatorial allocation of electric power in alternating current electric systems for smart grid"
    - "cost minimizing online algorithms for energy storage management with worst case guarantee"
    - "online algorithms for information aggregation from distributed and correlated sources"
    - "truthful mechanisms for combinatorial ac electric power allocation"
    - "online energy generation scheduling for microgrids with intermittent energy sources and co generation"

Connected through hyperedge HE-5 (induced by source paper "truthful mechanisms for combinatorial allocation of electric power in alternating current electric systems for smart grid"):
  with members:
    - "complex demand scheduling problem with application in smart grid"
    - "optimal power flow with inelastic demands for demand response in radial distribution networks"
    - "truthful mechanisms for combinatorial ac electric power allocation"
    - "mechanisms for multi unit auctions"
    - "computationally feasible vcg mechanisms"

Connected through hyperedge HE-6 (induced by source paper "approximation schemes for binary quadratic programming problems with low cp rank decompositions"):
  with members:
    - "truthful mechanisms for combinatorial ac electric power allocation"
    - "computing a nonnegative matrix factorization provably"
    - "submodular functions extensions distributions and algorithms a survey"
    - "on the complexity of nonnegative matrix factorization"

Connected through hyperedge HE-7 (induced by source paper "truthful mechanisms for combinatorial ac electric power allocation"):
  with members:
    - "mechanisms for multi unit auctions"
    - "computationally feasible vcg mechanisms"

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.DS(Data Structures and Algorithms)