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: "joining extractions of regular expressions"
  Abstract: Regular expressions with capture variables, also known as "regex formulas," extract relations of spans (interval positions) from text. These relations can be further manipulated via Relational Algebra as studied in the context of document spanners, Fagin et al.'s formal framework for information extraction. We investigate the complexity of querying text by Conjunctive Queries (CQs) and Unions of CQs (UCQs) on top of regex formulas. We show that the lower bounds (NP-completeness and W[1]-hardness) from the relational world also hold in our setting; in particular, hardness hits already single-character text! Yet, the upper bounds from the relational world do not carry over. Unlike the relational world, acyclic CQs, and even gamma-acyclic CQs, are hard to compute. The source of hardness is that it may be intractable to instantiate the relation defined by a regex formula, simply because it has an exponential number of tuples. Yet, we are able to establish general upper bounds. In particular, UCQs can be evaluated with polynomial delay, provided that every CQ has a bounded number of atoms (while unions and projection can be arbitrary). Furthermore, UCQ evaluation is solvable with FPT (Fixed-Parameter Tractable) delay when the parameter is the size of the UCQ.

Connected through hyperedge HE-1 (induced by source paper "grammars for document spanenrs"):
  with members:
    - "complexity bounds for relational algebra over document spanners"
    - "weight annotation in information extraction"
    - "finite models and the theory of concatenation"
    - "constant delay enumeration for nondeterministic document spanners"
    - "split correctness in information extraction"
    - "constant delay algorithms for regular document spanners"
    - "document spanners for extracting incomplete information expressiveness and complexity"
    - "recursive programs for document spanners"

Connected through hyperedge HE-2 (induced by source paper "the complexity of aggregates over extractions by regular expressions"):
  with members:
    - "complexity bounds for relational algebra over document spanners"
    - "constant delay enumeration for nondeterministic document spanners"
    - "constant delay algorithms for regular document spanners"

Connected through hyperedge HE-3 (induced by source paper "the theory of concatenation over finite models"):
  with members:
    - "dynamic complexity of document spanners"
    - "matching patterns with variables"
    - "weight annotation in information extraction"
    - "constant delay enumeration for nondeterministic document spanners"
    - "split correctness in information extraction"
    - "deterministic regular expressions with back references"
    - "constant delay algorithms for regular document spanners"
    - "the hardness of solving simple word equations"

Connected through hyperedge HE-4 (induced by source paper "weight annotation in information extraction"):
  with members:
    - "efficient logspace classes for enumeration counting and uniform generation"
    - "complexity bounds for relational algebra over document spanners"
    - "representing formal languages a comparison between finite automata and recurrent neural networks"
    - "constant delay enumeration for nondeterministic document spanners"
    - "constant delay algorithms for regular document spanners"
    - "document spanners for extracting incomplete information expressiveness and complexity"
    - "snorkel rapid training data creation with weak supervision"
    - "extracting automata from recurrent neural networks using queries and counterexamples"

Connected through hyperedge HE-5 (induced by source paper "complexity bounds for relational algebra over document spanners"):
  with members:
    - "rational recurrences"
    - "constant delay enumeration for nondeterministic document spanners"
    - "constant delay algorithms for regular document spanners"
    - "document spanners for extracting incomplete information expressiveness and complexity"
    - "extracting automata from recurrent neural networks using queries and counterexamples"
    - "enumeration complexity of conjunctive queries with functional dependencies"
    - "recursive programs for document spanners"
    - "semantics and complexity of sparql"

Connected through hyperedge HE-6 (induced by source paper "efficient logspace classes for enumeration counting and uniform generation"):
  with members:
    - "connecting knowledge compilation classes and width parameters"
    - "constant delay enumeration for nondeterministic document spanners"
    - "descriptive complexity for counting complexity classes"
    - "constant delay algorithms for regular document spanners"
    - "a circuit based approach to efficient enumeration"
    - "document spanners for extracting incomplete information expressiveness and complexity"
    - "foundations of modern query languages for graph databases"

Connected through hyperedge HE-7 (induced by source paper "conjunctive regular path queries with string variables"):
  with members:
    - "boundedness of conjunctive regular path queries"
    - "a trichotomy for regular trail queries"
    - "split correctness in information extraction"
    - "deterministic regular expressions with back references"
    - "an analytical study of large sparql query logs"
    - "foundations of modern query languages for graph databases"

Connected through hyperedge HE-8 (induced by source paper "constant delay enumeration for nondeterministic document spanners"):
  with members:
    - "enumeration on trees with tractable combined complexity and efficient updates"
    - "enumeration on trees under relabelings"
    - "constant delay algorithms for regular document spanners"
    - "answering fo mod queries under updates on bounded degree databases"
    - "a circuit based approach to efficient enumeration"
    - "answering conjunctive queries under updates"
    - "document spanners for extracting incomplete information expressiveness and complexity"
    - "answering ucqs under updates and in the presence of integrity constraints"

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)