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: "Level 5/2 of the Straubing-Thérien Hierarchy for Two-Letter Alphabets"
  Abstract: We prove an effective characterization of level 5/2 of the Straubing-Therien hierarchy for the restricted case of languages defined over a two-letter alphabet.

Connected through hyperedge HE-1 (induced by source paper "Languages of Dot-Depth 3/2"):
  with members:
    (none)

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