human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "finding all solutions of equations in free groups and monoids with involution"
  Abstract: The aim of this paper is to present a PSPACE algorithm which yields a finite graph of exponential size and which describes the set of all solutions of equations in free groups as well as the set of all solutions of equations in free monoids with involution in the presence of rational constraints. This became possible due to the recently invented emph{recompression} technique of the second author. #R##N#He successfully applied the recompression technique for pure word equations without involution or rational constraints. In particular, his method could not be used as a black box for free groups (even without rational constraints). Actually, the presence of an involution (inverse elements) and rational constraints complicates the situation and some additional analysis is necessary. Still, the recompression technique is general enough to accommodate both extensions. In the end, it simplifies proofs that solving word equations is in PSPACE (Plandowski 1999) and the corresponding result for equations in free groups with rational constraints (Diekert, Hagenah and Gutierrez 2001). As a byproduct we obtain a direct proof that it is decidable in PSPACE whether or not the solution set is finite.

Connected through hyperedge HE-1 (induced by source paper "solution sets for equations over free groups are edt0l languages icalp 2015 version"):
  with members:
    - "recompression a simple and powerful technique for word equations"
    - "the existential theory of equations with rational constraints in free groups is pspace complete"

Connected through hyperedge HE-2 (induced by source paper "more than 1700 years of word equations"):
  with members:
    - "recompression a simple and powerful technique for word equations"
    - "the existential theory of equations with rational constraints in free groups is pspace complete"

Connected through hyperedge HE-3 (induced by source paper "equations over free inverse monoids with idempotent variables"):
  with members:
    - "solution sets for equations over free groups are edt0l languages icalp 2015 version"
    - "recompression a simple and powerful technique for word equations"

Connected through hyperedge HE-4 (induced by source paper "recompression a simple and powerful technique for word equations"):
  with members:
    - "the complexity of compressed membership problems for finite automata"
    - "a really simple approximation of smallest grammar"
    - "approximation of grammar based compression via recompression"
    - "approximation of smallest linear tree grammar"
    - "context unification is in pspace"
    - "one variable word equations in linear time"
    - "faster fully compressed pattern matching by recompression"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.LO(Logic in Computer Science)