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: "an effective characterization of the alternation hierarchy in two variable logic"
  Abstract: We characterize the languages in the individual levels of the quantifier alternation hierarchy of first-order logic with two variables by identities. This implies decidability of the individual levels. More generally we show that the two-sided semidirect product of a decidable variety with the variety J is decidable.

Connected through hyperedge HE-1 (induced by source paper "wreath products of distributive forest algebras"):
  with members:
    - "going higher in the first order quantifier alternation hierarchy on words"
    - "piecewise testable tree languages"
    - "wreath products of forest algebras with applications to tree logics"
    - "a decidable characterization of locally testable tree languages"
    - "tree languages defined in first order logic with one quantifier alternation"

Connected through hyperedge HE-2 (induced by source paper "finite degree predicates and two variable first order logic"):
  with members:
    - "non definability of languages by generalized first order formulas over n"
    - "structure theorem and strict alternation hierarchy for fo2 on words"

Connected through hyperedge HE-3 (induced by source paper "using duality in circuit complexity"):
  with members:
    - "logic meets algebra the case of regular languages"

Connected through hyperedge HE-4 (induced by source paper "from algebra to logic there and back again the story of a hierarchy"):
  with members:
    - "essential convexity and complexity of semi algebraic constraints"
    - "the fo2 alternation hierarchy is decidable"
    - "representations of stream processors using nested fixed points"
    - "structure theorem and strict alternation hierarchy for fo2 on words"

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)