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: "on the complexity of xpath containment in the presence of disjunction dtds and variables"
  Abstract: XPath is a simple language for navigating an XML-tree and returning a set of#N#answer nodes. The focus in this paper is on the complexity of the containment#N#problem for various fragments of XPath. We restrict attention to the most#N#common XPath expressions which navigate along the child and/or descendant axis.#N#In addition to basic expressions using only node tests and simple predicates,#N#we also consider disjunction and variables (ranging over nodes). Further, we#N#investigate the containment problem relative to a given DTD. With respect to#N#variables we study two semantics, (1) the original semantics of XPath, where#N#the values of variables are given by an outer context, and (2) an existential#N#semantics introduced by Deutsch and Tannen, in which the values of variables#N#are existentially quantified. In this framework, we establish an exact#N#classification of the complexity of the containment problem for many XPath#N#fragments.

Connected through hyperedge HE-1 (induced by source paper "containment of simple regular path queries"):
  with members:
    - "an analytical study of large sparql query logs"

Connected through hyperedge HE-2 (induced by source paper "schemas for unordered xml on a dime"):
  with members:
    - "validating rdf with shape expressions"
    - "simple schemas for unordered xml"
    - "learning schemas for unordered xml"

Connected through hyperedge HE-3 (induced by source paper "learning deterministic regular expressions for the inference of schemas from xml data"):
  with members:
    - "succinctness of the complement and intersection of regular expressions"
    - "schema based scheduling of event processors and buffer minimization for queries on structured data streams"

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)