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: "multi keyword multi click advertisement option contracts for sponsored search"
  Abstract: In sponsored search, advertisement (abbreviated ad) slots are usually sold by a search engine to an advertiser through an auction mechanism in which advertisers bid on keywords. In theory, auction mechanisms have many desirable economic properties. However, keyword auctions have a number of limitations including: the uncertainty in payment prices for advertisers; the volatility in the search engine's revenue; and the weak loyalty between advertiser and search engine. In this paper we propose a special ad option that alleviates these problems. In our proposal, an advertiser can purchase an option from a search engine in advance by paying an upfront fee, known as the option price. He then has the right, but no obligation, to purchase among the pre-specified set of keywords at the fixed cost-per-clicks (CPCs) for a specified number of clicks in a specified period of time. The proposed option is closely related to a special exotic option in finance that contains multiple underlying assets (multi-keyword) and is also multi-exercisable (multi-click). This novel structure has many benefits: advertisers can have reduced uncertainty in advertising; the search engine can improve the advertisers' loyalty as well as obtain a stable and increased expected revenue over time. Since the proposed ad option can be implemented in conjunction with the existing keyword auctions, the option price and corresponding fixed CPCs must be set such that there is no arbitrage between the two markets. Option pricing methods are discussed and our experimental results validate the development. Compared to keyword auctions, a search engine can have an increased expected revenue by selling an ad option.

Connected through hyperedge HE-1 (induced by source paper "pricing average price advertising options when underlying spot market prices are discontinuous"):
  with members:
    - "risk aware dynamic reserve prices of programmatic guarantee in display advertising"
    - "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"
    - "a lattice framework for pricing display advertisement options with the stochastic volatility underlying model"
    - "real time bidding for online advertising measurement and analysis"
    - "shale an efficient algorithm for allocation of guaranteed display advertising"
    - "sequential selection of correlated ads by pomdps"

Connected through hyperedge HE-2 (induced by source paper "combining guaranteed and spot markets in display advertising selling guaranteed page views with stochastic demand"):
  with members:
    - "pricing average price advertising options when underlying spot market prices are discontinuous"
    - "risk aware dynamic reserve prices of programmatic guarantee in display advertising"
    - "ad exchange envy free auctions with mediators"
    - "efficient delivery policy to minimize user traffic consumption in guaranteed advertising"
    - "combining spot and futures markets a hybrid market approach to dynamic spectrum access"
    - "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"
    - "a lattice framework for pricing display advertisement options with the stochastic volatility underlying model"
    - "shale an efficient algorithm for allocation of guaranteed display advertising"

Connected through hyperedge HE-3 (induced by source paper "optimizing trade offs among stakeholders in real time bidding by incorporating multimedia metrics"):
  with members:
    - "risk aware dynamic reserve prices of programmatic guarantee in display advertising"
    - "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"
    - "optimising trade offs among stakeholders in ad auctions"
    - "a lattice framework for pricing display advertisement options with the stochastic volatility underlying model"
    - "ranking and tradeoffs in sponsored search auctions"

Connected through hyperedge HE-4 (induced by source paper "risk aware dynamic reserve prices of programmatic guarantee in display advertising"):
  with members:
    - "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"
    - "a lattice framework for pricing display advertisement options with the stochastic volatility underlying model"
    - "shale an efficient algorithm for allocation of guaranteed display advertising"
    - "bidding for representative allocations for display advertising"

Connected through hyperedge HE-5 (induced by source paper "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"):
  with members:
    - "real time bidding for online advertising measurement and analysis"
    - "shale an efficient algorithm for allocation of guaranteed display advertising"
    - "sequential selection of correlated ads by pomdps"
    - "bidding for representative allocations for display advertising"

Connected through hyperedge HE-6 (induced by source paper "a lattice framework for pricing display ad options with the stochastic volatility underlying model"):
  with members:
    - "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"
    - "real time bidding for online advertising measurement and analysis"
    - "sequential selection of correlated ads by pomdps"

Connected through hyperedge HE-7 (induced by source paper "a lattice framework for pricing display advertisement options with the stochastic volatility underlying model"):
  with members:
    - "a dynamic pricing model for unifying programmatic guarantee and real time bidding in display advertising"
    - "real time bidding for online advertising measurement and analysis"
    - "sequential selection of correlated ads by pomdps"

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)