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 "Classifier for Activities with Variations"):
  Abstract: {}

Includes members:
  Member "Learning multi-level features for sensor-based human action recognition":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "Similar gait action recognition using an inertial sensor")

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: Engineering