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: "context free path queries on rdf graphs"
  Abstract: Navigational graph queries are an important class of queries that canextract implicit binary relations over the nodes of input graphs. Most of the navigational query languages used in the RDF community, e.g. property paths in W3C SPARQL 1.1 and nested regular expressions in nSPARQL, are based on the regular expressions. It is known that regular expressions have limited expressivity; for instance, some natural queries, like same generation-queries, are not expressible with regular expressions. To overcome this limitation, in this paper, we present cfSPARQL, an extension of SPARQL query language equipped with context-free grammars. The cfSPARQL language is strictly more expressive than property paths and nested expressions. The additional expressivity can be used for modelling graph similarities, graph summarization and ontology alignment. Despite the increasing expressivity, we show that cfSPARQL still enjoys a low computational complexity and can be evaluated efficiently.

Connected through hyperedge HE-1 (induced by source paper "understanding data science lifecycle provenance via graph segmentation and summarization"):
  with members:
    - "consistently faster and smaller compressed bitmaps with roaring"
    - "foundations of modern query languages for graph databases"
    - "keystoneml optimizing pipelines for large scale advanced analytics"
    - "aggregation by provenance types a technique for summarising provenance graphs"
    - "provabs model policy and tooling for abstracting prov graphs"
    - "openml networked science in machine learning"

Connected through hyperedge HE-2 (induced by source paper "context free path querying by matrix multiplication"):
  with members:
    - "context free path querying with structural representation of result"
    - "querying for paths in graphs using context free path queries"

Connected through hyperedge HE-3 (induced by source paper "piwd a plugin based framework for well designed sparql"):
  with members:
    - "on the statistical analysis of practical sparql queries"
    - "efficient approximation of well designed sparql queries"
    - "left bit right for sparql join queries with optional patterns left outer joins"
    - "processing sparql queries over distributed rdf graphs"
    - "on the satisfiability problem for sparql patterns"
    - "efficient subgraph matching on billion node graphs"
    - "foundations of sparql query optimization"
    - "semantics and complexity of sparql"

Connected through hyperedge HE-4 (induced by source paper "path discovery by querying the federation of relational database and rdf graph"):
  with members:
    - "relative expressive power of navigational querying on graphs"
    - "on the satisfiability problem for sparql patterns"
    - "efficient external memory bisimulation on dags"
    - "semantics and complexity of sparql"

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.DB(Databases)