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: "Formal methods for protocol testing: a detailed study"
  Abstract: The authors present a detailed study of four formal methods (T-, U-, D-, and W-methods) for generating test sequences for protocols. Applications of these methods to the NBS Class 4 Transport Protocol are discussed. An estimation of fault coverage of four protocol-test-sequence generation techniques using Monte Carlo simulation is also presented. The ability of a test sequence to decide whether a protocol implementation conforms to its specification heavily relies on the range of faults that it can capture. Conformance is defined at two levels, namely, weak and strong conformance. This study shows that a test sequence produced by T-method has a poor fault detection capability, whereas test sequences produced by U-, D-, and W-methods have comparable (superior to that for T-method) fault coverage on several classes of randomly generated machines used in this study. Also, some problems with a straightforward application of the four protocol-test-sequence generation methods to real-world communication protocols are pointed out. >

Connected through hyperedge HE-1 (induced by source paper "Test development for communication protocols: towards automation"):
  with members:
    - "A protocol test generation procedure"
    - "A Systematic Approach to Automatically Derive Test Cases from Use Cases Specified in Restricted Natural Languages"

Connected through hyperedge HE-2 (induced by source paper "Bounded sequence testing from deterministic finite state machines"):
  with members:
    - "Model learning and test generation for event-b decomposition"

Connected through hyperedge HE-3 (induced by source paper "Validation-based test sequence generation for networks of extended finite state machines"):
  with members:
    - "A protocol test generation procedure"

Connected through hyperedge HE-4 (induced by source paper "A protocol test generation procedure"):
  with members:
    - "A reduced test suite for protocol conformance testing"
    - "Test development for communication protocols: towards automation"
    - "Validation-based test sequence generation for networks of extended finite state machines"

Connected through hyperedge HE-5 (induced by source paper "A reduced test suite for protocol conformance testing"):
  with members:
    - "A protocol test generation procedure"
    - "Toward automatic generation of novice user test scripts"

Connected through hyperedge HE-6 (induced by source paper "Online minimization of transition systems (extended abstract)"):
  with members:
    - "An implementation of three algorithms for timing verification based on automata emptiness"

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