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: "Image Restoration with Discrete Constrained Total Variation Part I: Fast and Exact Optimization"
  Abstract: This paper deals with the total variation minimization problem in image restoration for convex data fidelity functionals. We propose a new and fast algorithm which computes an exact solution in the discrete framework. Our method relies on the decomposition of an image into its level sets. It maps the original problems into independent binary Markov Random Field optimization problems at each level. Exact solutions of these binary problems are found thanks to minimum cost cut techniques in graphs. These binary solutions are proved to be monotone increasing with levels and yield thus an exact solution of the discrete original problem. Furthermore we show that minimization of total variation under L 1 data fidelity term yields a self-dual contrast invariant filter. Finally we present some results.

Connected through hyperedge HE-1 (induced by source paper "A fast parametric maximum flow algorithm and applications"):
  with members:
    - "On the hardness of approximating spanners"
    - "A new approach to the maximum flow problem"

Connected through hyperedge HE-2 (induced by source paper "Efficient Schemes for Total Variation Minimization Under Constraints in Image Processing"):
  with members:
    - "Convex optimization for multi-class image labeling with a novel family of total variation based regularizers"

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