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: "On the optimal compression of sets in PSPACE"
  Abstract: We show that if DTIME[2O(n)] is not included in DSPACE [2O(n)], then, for every set B in PSPACE, all strings x in B of length n can be represented by a string compressed(x) of length at most log(|B=n|) + O(log n), such that a polynomial-time algorithm, given compressed(x), can distinguish x from all the other strings in B=n. Modulo the O(log n) additive term, this achieves the information-theoretical optimum for string compression.

Connected through hyperedge HE-1 (induced by source paper "Improving the Space-Bounded Version of Muchnik's Conditional Complexity Theorem via Naive Derandomization"):
  with members:
    (none)

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: Mathematics