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: "similarity and bisimilarity notions appropriate for characterizing indistinguishability in fragments of the calculus of relations"
  Abstract: Motivated by applications in databases, this article considers various fragments of the calculus of binary relations. The fragments are obtained by leaving out, or keeping in, some of the standard operators, along with some derived operators such as set difference, projection, coprojection and residuation. For each considered fragment, a characterization is obtained for when two given binary relational structures are indistinguishable by expressions in that fragment. The characterizations are based on appropriately adapted notions of simulation and bisimulation.

Connected through hyperedge HE-1 (induced by source paper "structural indexing for conjunctive path queries"):
  with members:
    - "the ubiquity of large graphs and surprising challenges of graph processing extended survey"
    - "survey and taxonomy of lossless graph compression and space efficient graph representations"
    - "gmark schema driven generation of graphs and queries"
    - "g core a core for future graph query languages"
    - "an analytical study of large sparql query logs"
    - "foundations of modern query languages for graph databases"
    - "taming subgraph isomorphism for rdf query processing"
    - "relative expressive power of navigational querying on graphs"

Connected through hyperedge HE-2 (induced by source paper "structural characterizations of the navigational expressiveness of relation algebras on a tree"):
  with members:
    - "relative expressive power of navigational querying on graphs"

Connected through hyperedge HE-3 (induced by source paper "relative expressive power of navigational querying on graphs"):
  with members:
    - "undecidability of satisfiability in the algebra of finite binary relations with union composition and difference"

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)