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: "A new approach to the maximum flow problem"
  Abstract: All previously known efftcient maximum-flow algorithms work by finding augmenting paths, either one path at a time (as in the original Ford and Fulkerson algorithm) or all shortest-length augmenting paths at once (using the layered network approach of Dinic). An alternative method based on the preflow concept of Karzanov is introduced. A preflow is like a flow, except that the total amount flowing into a vertex is allowed to exceed the total amount flowing out. The method maintains a preflow in the original network and pushes local flow excess toward the sink along what are estimated to be shortest paths. The algorithm and its analysis are simple and intuitive, yet the algorithm runs as fast as any other known method on dense. graphs, achieving an O(n)) time bound on an n-vertex graph. By incorporating the dynamic tree data structure of Sleator and Tarjan, we obtain a version of the algorithm running in O(nm log(n'/m)) time on an n-vertex, m-edge graph. This is as fast as any known method for any graph density and faster on graphs of moderate density. The algorithm also admits efticient distributed and parallel implementations. A parallel implementation running in O(n'log n) time using n processors and O(m) space is obtained. This time bound matches that of the Shiloach-Vishkin

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"
    - "Image Restoration with Discrete Constrained Total Variation Part I: Fast and Exact Optimization"

Connected through hyperedge HE-2 (induced by source paper "Evaluation and improvement of Boolean comparison method based on binary decision diagrams"):
  with members:
    - "Using BDDs to verify multipliers"

Connected through hyperedge HE-3 (induced by source paper "Improved time bounds for the maximum flow problem"):
  with members:
    (none)

Connected through hyperedge HE-4 (induced by source paper "Efficient conflict driven learning in a boolean satisfiability solver"):
  with members:
    - "Solving SAT and SAT Modulo Theories: From an abstract Davis--Putnam--Logemann--Loveland procedure to DPLL( T )"
    - "Analysis of Search Based Algorithms for Satisfiability of Quantified Boolean Formulas Arising from Circuit State Space Diameter Problems."
    - "Lazy explanations for constraint propagators"
    - "Efficient Solving of Large Non-linear Arithmetic Constraint Systems with Complex Boolean Structure"

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