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: "Schema-based Query Optimization for XQuery Queries."
  Abstract: XQuery is widely used for querying XML documents. Within this paper, we examine optimization rules for XQuery queries that exploit type information of the input XML document given in XML Schema. These optimization rules are applicable for all XQuery expressions and are very useful e.g. in the scenario of XQuery queries on XQuery views. The basic idea is to transform the XML Schema definition into a graph, which is extended to a graph representing the XQuery expression. The latter graph is used to delete subexpressions of the XQuery expression that are not used to retrieve the final result of the given XQuery expression. We further include experimental results that demonstrate the improvement of our optimization.

Connected through hyperedge HE-1 (induced by source paper "XPath Query Simplification with regard to the Elimination of Intersect and Except Operators"):
  with members:
    - "FILTERING UNSATISFIABLE XPATH QUERIES"

Connected through hyperedge HE-2 (induced by source paper "Algebraic Transformation and Optimization for XQuery"):
  with members:
    - "An Algebra for XML Query"

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: Computer science