human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "bisimilarity on basic process algebra is in 2 exptime an explicit proof"):
  Abstract: Burkart, Caucal, Steffen (1995) showed a procedure deciding bisimulation#N#equivalence of processes in Basic Process Algebra (BPA), i.e. of sequential#N#processes generated by context-free grammars. They improved the previous#N#decidability result of Christensen, H\"uttel, Stirling (1992), since their#N#procedure has obviously an elementary time complexity and the authors claim#N#that a close analysis would reveal a double exponential upper bound. Here a#N#self-contained direct proof of the membership in 2-ExpTime is given. This is#N#done via a Prover-Refuter game which shows that there is an alternating Turing#N#machine deciding the problem in exponential space. The proof uses similar#N#ingredients (size-measures, decompositions, bases) as the previous proofs, but#N#one new simplifying factor is an explicit addition of infinite regular strings#N#to the state space. An auxiliary claim also shows an explicit exponential upper#N#bound on the equivalence level of nonbisimilar normed BPA processes. The#N#importance of clarifying the 2-ExpTime upper bound for BPA bisimilarity has#N#recently increased due to the shift of the known lower bound from PSpace (Srba,#N#2002) to ExpTime (Kiefer, 2012).

Includes members:
  Member "bisimilarity of pushdown systems is nonelementary":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "deciding semantic finiteness of pushdown processes and first order grammars w r t bisimulation equivalence")
  Member "bpa bisimilarity is exptime hard":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "bisimulation equivalence of first order grammars is ackermann complete")
  Member "beyond language equivalence on visibly pushdown automata":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "bisimulation equivalence of first order grammars is ackermann complete")
  Member "the bisimulation problem for equational graphs of finite out degree":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "bisimulation equivalence of first order grammars is ackermann complete")

Question: Please tell me which class the source paper 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)