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: "generic expression hardness results for primitive positive formula comparison"
  Abstract: We study the expression complexity of two basic problems involving the comparison of primitive positive formulas: equivalence and containment. In particular, we study the complexity of these problems relative to finite relational structures. We present two generic hardness results for the studied problems, and discuss evidence that they are optimal and yield, for each of the problems, a complexity trichotomy.

Connected through hyperedge HE-1 (induced by source paper "testing assignments to constraint satisfaction problems"):
  with members:
    - "sherali adams relaxations for valued csps"
    - "approximate constraint satisfaction requires large lp relaxations"
    - "the power of linear programming for valued csps"
    - "testing list h homomorphisms"
    - "an effective dichotomy for the counting constraint satisfaction problem"
    - "the complexity of global cardinality constraints"

Connected through hyperedge HE-2 (induced by source paper "asking the metaquestions in constraint tractability"):
  with members:
    - "meditations on quantified constraint satisfaction"
    - "arc consistency and friends"
    - "peek arc consistency"

Connected through hyperedge HE-3 (induced by source paper "meditations on quantified constraint satisfaction"):
  with members:
    - "the complexity of quantified constraint satisfaction collapsibility sink algebras and the three element case"
    - "existentially restricted quantified constraint satisfaction"

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)