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: "frugality ratios and improved truthful mechanisms for vertex cover"
  Abstract: In {\em set-system auctions}, there are several overlapping teams of agents, and a task that can be completed by any of these teams. The buyer's goal is to hire a team and pay as little as possible. Recently, Karlin, Kempe and Tamir introduced a new definition of {\em frugality ratio} for this setting. Informally, the frugality ratio is the ratio of the total payment of a mechanism to perceived fair cost. In this paper, we study this together with alternative notions of fair cost, and how the resulting frugality ratios relate to each other for various kinds of set systems. #R##N#We propose a new truthful polynomial-time auction for the vertex cover problem (where the feasible sets correspond to the vertex covers of a given graph), based on the {\em local ratio} algorithm of Bar-Yehuda and Even. The mechanism guarantees to find a winning set whose cost is at most twice the optimal. In this situation, even though it is NP-hard to find a lowest-cost feasible set, we show that {\em local optimality} of a solution can be used to derive frugality bounds that are within a constant factor of best possible. To prove this result, we use our alternative notions of frugality via a bootstrapping technique, which may be of independent interest.

Connected through hyperedge HE-1 (induced by source paper "optimal budget feasible mechanisms for additive valuations"):
  with members:
    - "on budget feasible mechanism design for symmetric submodular objectives"
    - "simple and efficient budget feasible mechanisms for monotone submodular valuations"
    - "budget feasible mechanisms on matroids"
    - "coverage matching and beyond new results on budgeted mechanism design"
    - "bayesian budget feasibility with posted pricing"
    - "mechanism design for crowdsourcing an optimal 1 1 e competitive budget feasible mechanism for large markets"
    - "budget feasible mechanisms for experimental design"
    - "on the approximability of budget feasible mechanisms"

Connected through hyperedge HE-2 (induced by source paper "core competitive auctions"):
  with members:
    - "prior free auctions for budgeted agents"
    - "mechanism design via consensus estimates cross checking and profit extraction"
    - "frugal mechanism design via spectral techniques"
    - "frugal and truthful auctions for vertex covers flows and cuts"

Connected through hyperedge HE-3 (induced by source paper "price competition in online combinatorial markets"):
  with members:
    - "simultaneous auctions are almost efficient"
    - "sequential auctions and externalities"
    - "non price equilibria in markets of discrete goods"
    - "frugal mechanism design via spectral techniques"
    - "frugal and truthful auctions for vertex covers flows and cuts"
    - "combinatorial auctions with decreasing marginal utilities"

Connected through hyperedge HE-4 (induced by source paper "truthful mechanism design for multidimensional covering problems"):
  with members:
    - "the computational complexity of truthfulness in combinatorial auctions"
    - "from convex optimization to randomized mechanisms toward optimal combinatorial auctions"
    - "frugal mechanism design via spectral techniques"
    - "frugal and truthful auctions for vertex covers flows and cuts"
    - "greedy facility location algorithms analyzed using dual fitting with factor revealing lp"

Connected through hyperedge HE-5 (induced by source paper "benchmark problems for totally unimodular set system auction"):
  with members:
    - "frugal mechanism design via spectral techniques"
    - "frugal and truthful auctions for vertex covers flows and cuts"

Connected through hyperedge HE-6 (induced by source paper "frugal mechanism design via spectral techniques"):
  with members:
    - "false name proof mechanisms for hiring a team"
    - "frugal and truthful auctions for vertex covers flows and cuts"

Connected through hyperedge HE-7 (induced by source paper "frugal and truthful auctions for vertex covers flows and cuts"):
  with members:
    - "frugal mechanism design via spectral techniques"

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)