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: "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).

Connected through hyperedge HE-1 (induced by source paper "branching bisimilarity of normed bpa processes as a rational monoid"):
  with members:
    - "two lower bounds for bpa"
    - "branching bisimilarity on normed bpa is exptime complete"
    - "a polynomial time algorithm for deciding branching bisimilarity on totally normed bpa"
    - "branching bisimilarity of normed bpa processes is in nexptime"
    - "branching bisimilarity checking for prs"
    - "bpa bisimilarity is exptime hard"

Connected through hyperedge HE-2 (induced by source paper "branching bisimilarity on normed bpa is exptime complete"):
  with members:
    - "dividing line between decidable pda s and undecidable ones"
    - "a polynomial time algorithm for deciding branching bisimilarity on totally normed bpa"
    - "branching bisimilarity of normed bpa processes is in nexptime"
    - "branching bisimilarity checking for prs"
    - "bpa bisimilarity is exptime hard"
    - "equivalence checking on infinite state systems techniques and results"

Connected through hyperedge HE-3 (induced by source paper "bisimulation equivalence of first order grammars"):
  with members:
    - "complexity hierarchies beyond elementary"
    - "dividing line between decidable pda s and undecidable ones"
    - "branching bisimilarity checking for prs"
    - "bpa bisimilarity is exptime hard"
    - "on the complexity of the equivalence problem for probabilistic automata"
    - "the bisimulation problem for equational graphs of finite out degree"

Connected through hyperedge HE-4 (induced by source paper "branching bisimilarity of normed bpa processes is in nexptime"):
  with members:
    - "branching bisimilarity on normed bpa is exptime complete"
    - "a polynomial time algorithm for deciding branching bisimilarity on totally normed bpa"
    - "branching bisimilarity checking for prs"
    - "bpa bisimilarity is exptime hard"

Connected through hyperedge HE-5 (induced by source paper "bpa bisimilarity is exptime hard"):
  with members:
    - "beyond language equivalence on visibly pushdown automata"
    - "decidability of higher order matching"
    - "model checking probabilistic timed automata with one or two clocks"
    - "equivalence checking on infinite state systems techniques and results"
    - "the bisimulation problem for equational graphs of finite out degree"

Connected through hyperedge HE-6 (induced by source paper "bisimilarity of probabilistic pushdown automata"):
  with members:
    - "bpa bisimilarity is exptime hard"
    - "beyond language equivalence on visibly pushdown automata"
    - "the bisimulation problem for equational graphs of finite out degree"

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)