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: "Retro: time-based exploration of product reviews"
  Abstract: Most e-commerce websites organize and present product reviews around ratings with hardly any feature to view them in a time-oriented way. Often, there is a way to sort reviews by time but no further temporal analysis is possible. Thus, usually, only few reviews are part of a user's review analysis process, and there is no way to analyze all reviews of a product collectively. In this paper, we describe Retro, a search engine for exploring product reviews using temporal information.

Connected through hyperedge HE-1 (induced by source paper "Utility scoring of product reviews"):
  with members:
    - "Opinion Mining and Sentiment Analysis"
    - "Opinion observer: analyzing and comparing opinions on the Web"
    - "Toward a fair review-management system"

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