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: "almost efficient mechanisms for bilateral trading"
  Abstract: We study the simplest form of two-sided markets: one seller, one buyer and a single item for sale. It is well known that there is no fully-efficient mechanism for this problem that maintains a balanced budget. We characterize the quality of the most efficient mechanisms that are budget balanced, and design simple and robust mechanisms with these properties. We also show that even minimal use of statistical data can yield good results. Finally, we demonstrate how a mechanism for this simple bilateral-trade problem can be used as a "black-box" for constructing mechanisms in more general environments.

Connected through hyperedge HE-1 (induced by source paper "efficient two sided markets with limited information"):
  with members:
    - "optimal single choice prophet inequalities from samples"
    - "bulow klemperer style results for welfare maximization in two sided markets"
    - "improved truthful mechanisms for combinatorial auctions with submodular bidders"
    - "online trading as a secretary problem"
    - "the best of both worlds asymptotically efficient mechanisms with a guarantee on the expected gains from trade"
    - "approximating gains from trade in two sided markets via simple mechanisms"
    - "fixed price approximability of the optimal gain from trade"
    - "online market intermediation"

Connected through hyperedge HE-2 (induced by source paper "bulow klemperer style results for welfare maximization in two sided markets"):
  with members:
    - "the vickrey auction with a single duplicate bidder approximates the optimal revenue"
    - "99 revenue via enhanced competition"
    - "the best of both worlds asymptotically efficient mechanisms with a guarantee on the expected gains from trade"
    - "are two samples really better than one on the non asymptotic performance of empirical revenue maximization"
    - "optimal and benchmark optimal competition complexity for additive buyers over independent items"
    - "approximating gains from trade in two sided markets via simple mechanisms"
    - "submultiplicative glivenko cantelli and uniform convergence of revenues"
    - "a general theory of sample complexity for multi item profit maximization"

Connected through hyperedge HE-3 (induced by source paper "simple mechanisms for profit maximization in multi item auctions"):
  with members:
    - "the best of both worlds asymptotically efficient mechanisms with a guarantee on the expected gains from trade"
    - "a duality based unified approach to bayesian mechanism design"
    - "approximating gains from trade in two sided markets via simple mechanisms"
    - "approximate revenue maximization with multiple items"
    - "simple mechanisms for subadditive buyers via duality"
    - "mechanism design for subadditive agents via an ex ante relaxation"
    - "approximately efficient two sided combinatorial auctions"
    - "online contention resolution schemes"

Connected through hyperedge HE-4 (induced by source paper "multi unit bilateral trade"):
  with members:
    - "online trading as a secretary problem"
    - "approximating gains from trade in two sided markets via simple mechanisms"
    - "fixed price approximability of the optimal gain from trade"
    - "muda a truthful multi unit double auction mechanism"
    - "online market intermediation"
    - "online truthful mechanisms for multi sided markets"
    - "simple and near optimal mechanisms for market intermediation"

Connected through hyperedge HE-5 (induced by source paper "the best of both worlds asymptotically efficient mechanisms with a guarantee on the expected gains from trade"):
  with members:
    - "approximating gains from trade in two sided markets via simple mechanisms"

Connected through hyperedge HE-6 (induced by source paper "approximately efficient two sided combinatorial auctions"):
  with members:
    - "the best of both worlds asymptotically efficient mechanisms with a guarantee on the expected gains from trade"
    - "approximating gains from trade in two sided markets via simple mechanisms"
    - "fixed price approximability of the optimal gain from trade"
    - "sbba a strongly budget balanced double auction mechanism"
    - "combinatorial auctions via posted prices"
    - "polymatroid prophet inequalities"
    - "matroid prophet inequalities"

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.GT(Computer Science and Game Theory)