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: "payment network design with fees"
  Abstract: Payment channels are the most prominent solution to the blockchain scalability problem. We introduce the problem of network design with fees for payment channels from the perspective of a Payment Service Provider (PSP). Given a set of transactions, we examine the optimal graph structure and fee assignment to maximize the PSP's profit. A customer prefers to route transactions through the PSP's network if the cheapest path from sender to receiver is financially interesting, i.e., if the path costs less than the blockchain fee. When the graph structure is a tree, and the PSP facilitates all transactions, the problem can be formulated as a linear program. For a path graph, we present a polynomial time algorithm to assign optimal fees. We also show that the star network, where the center is an additional node acting as an intermediary, is a near-optimal solution to the network design problem.

Connected through hyperedge HE-1 (induced by source paper "a cryptoeconomic traffic analysis of bitcoins lightning network"):
  with members:
    - "privacy utility tradeoffs in routing cryptocurrency over payment channel networks"
    - "topological analysis of bitcoin s lightning network"
    - "the evolution of lightning network s topology during its first year and the influence over its core values"
    - "payment networks as creation games"
    - "discharged payment channels quantifying the lightning network s resilience to topology based attacks"
    - "ant routing algorithm for the lightning network"
    - "towards an economic analysis of routing in payment channel networks"
    - "sprites and state channels payment networks that go faster than lightning"

Connected through hyperedge HE-2 (induced by source paper "how to profit from payments channels"):
  with members:
    - "discharged payment channels quantifying the lightning network s resilience to topology based attacks"
    - "celer network bring internet scale to every blockchain"
    - "towards an economic analysis of routing in payment channel networks"
    - "sprites and state channels payment networks that go faster than lightning"
    - "how to charge lightning"
    - "improving the betweenness centrality of a node by adding links"
    - "settling payments fast and private efficient decentralized routing for path based transactions"

Connected through hyperedge HE-3 (induced by source paper "online payment network design"):
  with members:
    - "brick asynchronous state channels"
    - "sprites and state channels payment networks that go faster than lightning"
    - "settling payments fast and private efficient decentralized routing for path based transactions"

Connected through hyperedge HE-4 (induced by source paper "ride the lightning the game theory of payment channels"):
  with members:
    - "brick asynchronous state channels"
    - "a bounded budget network creation game"

Connected through hyperedge HE-5 (induced by source paper "payment networks as creation games"):
  with members:
    - "brick asynchronous state channels"
    - "settling payments fast and private efficient decentralized routing for path based transactions"

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)