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: "learning and verifying quantified boolean queries by example"
  Abstract: To help a user specify and verify quantified queries --- a class of database queries known to be very challenging for all but the most expert users --- one can question the user on whether certain data objects are answers or non-answers to her intended query. In this paper, we analyze the number of questions needed to learn or verify qhorn queries, a special class of Boolean quantified queries whose underlying form is conjunctions of quantified Horn expressions. We provide optimal polynomial-question and polynomial-time learning and verification algorithms for two subclasses of the class qhorn with upper constant limits on a query's causal density.

Connected through hyperedge HE-1 (induced by source paper "example driven query intent discovery abductive reasoning using semantic similarity"):
  with members:
    - "learning from positive and unlabeled data a survey"
    - "the complexity of reverse engineering problems for conjunctive queries"
    - "causes for query answers from databases datalog abduction view updates and integrity constraints"
    - "compositional vector space models for knowledge base completion"
    - "querying knowledge graphs by example entity tuples"
    - "coherent integration of databases by abductive logic programming"

Connected through hyperedge HE-2 (induced by source paper "learning definable hypotheses on trees"):
  with members:
    - "learning first order definable concepts over structures of small degree"
    - "machine learning with guarantees using descriptive complexity and smt solvers"
    - "abstract learning frameworks for synthesis"

Connected through hyperedge HE-3 (induced by source paper "learning first order definable concepts over structures of small degree"):
  with members:
    - "machine learning with guarantees using descriptive complexity and smt solvers"
    - "abstract learning frameworks for synthesis"
    - "first order query evaluation on structures of bounded degree"

Connected through hyperedge HE-4 (induced by source paper "a signaling game approach to databases querying and interaction"):
  with members:
    - "modeling collaboration in academia a game theoretic approach"
    - "games for active xml revisited"
    - "optimal aggregation algorithms for middleware"

Connected through hyperedge HE-5 (induced by source paper "schema independent relational learning"):
  with members:
    - "the madlib analytics library or mad skills the sql"

Connected through hyperedge HE-6 (induced by source paper "representation independent analytics over structured data"):
  with members:
    - "the madlib analytics library or mad skills the sql"

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)