human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge groups authors who co-authored the same paper.

Details of the hypergraph:
Center hyperedge (induced by source paper "On the μ-calculus over transitive and finite transitive frames"):
  Abstract: We prove that the modal @m-calculus collapses to first order logic over the class of finite transitive frames. The proof is obtained by using some byproducts of a new proof of the collapse of the @m-calculus to the alternation free fragment over the class of transitive frames. Moreover, we prove that the modal @m-calculus is Buchi and co-Buchi definable over the class of all models where, in a strongly connected component, vertexes are distinguishable by means of the propositions they satisfy.

Includes members:
  Member "Modal characterisation theorems over special classes of frames":
    also connected through other hyperedges:
      (none)

Question: Please tell me which research area the co-authored paper (i.e., the source paper of the center hyperedge) belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Mathematics