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 "Commutative grammars: the complexity of uniform word problems"):
  Abstract: Commutative grammars are introduced, and various classes of commutative grammars are defined. The complexity of uniform word problems for commutative grammars is investigated.

Includes members:
  Member "On the equivalence, containment, and covering problems for the regular and context-free languages":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "On the complexity of grammar and related problems")
  Member "Conjunctive and Boolean grammars: The true general case of the context-free grammars":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "Recognizing Two-Sided Contexts in Cubic Time")

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