human: Given a node-centered hypergraph: <hypergraph>, where nodes represent authors and hyperedges represent groups of authors who co-authored the same paper.

Details of the hypergraph:
Center node: "Efficient learning equilibrium"
  Abstract: We introduce efficient learning equilibrium (ELE), a normative approach to learning in noncooperative settings. In ELE, the learning algorithms themselves are required to be in equilibrium. In addition, the learning algorithms must arrive at a desired value after polynomial time, and a deviation from the prescribed ELE becomes irrational after polynomial time. We prove the existence of an ELE (where the desired value is the expected payoff in a Nash equilibrium) and of a Pareto-ELE (where the objective is the maximization of social surplus) in repeated games with perfect monitoring. We also show that an ELE does not always exist in the imperfect monitoring case. Finally, we discuss the extension of these results to general-sum stochastic games.

Connected through hyperedge HE-1 (induced by source paper "Playing Games without Observing Payoffs"):
  with members:
    (none)

Connected through hyperedge HE-2 (induced by source paper "Bundling equilibrium in combinatorial auctions"):
  with members:
    - "i Bundle: an efficient ascending price bundle auction"

Question: Please tell me which research area the center author belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Mathematics