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 "Polynomial algorithms for graph isomorphism and chromatic index on partial k -trees"):
  Abstract: In this paper we show that Graph Isomorphism and Chromatic Index are solvable in polynomial time when restricted to the class of graphs with treewidth ≤k (k a constant) (or equivalently, the class of partial k-trees). Also, we show that there exist algorithms that find tree-decompositions with treewidth ≤k of graphs with treewidth ≤k, in O(n3) time, (k constant).

Includes members:
  Member "NC-Algorithms for Graphs with Small Treewidth":
    also connected through other hyperedges:
      (none)
  Member "The Computational Structure of Monotone Monadic SNP and Constraint Satisfaction: A Study through Datalog and Group Theory":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "A dichotomy theorem for constraint satisfaction problems on a 3-element set")

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