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: "a trichotomy in the complexity of counting answers to conjunctive queries"
  Abstract: Conjunctive queries are basic and heavily studied database queries; in relational algebra, they are the select-project-join queries. In this article, we study the fundamental problem of counting, given a conjunctive query and a relational database, the number of answers to the query on the database. In particular, we study the complexity of this problem relative to sets of conjunctive queries. We present a trichotomy theorem, which shows essentially that this problem on a set of conjunctive queries is either tractable, equivalent to the parameterized CLIQUE problem, or as hard as the parameterized counting CLIQUE problem; the criteria describing which of these situations occurs is simply stated, in terms of graph-theoretic conditions.

Connected through hyperedge HE-1 (induced by source paper "counting answers to existential questions"):
  with members:
    - "homomorphisms are a good basis for counting small subgraphs"
    - "homomorphisms are indeed a good basis for counting three fixed template dichotomy theorems for the price of one"
    - "note on the complexity of counting surjective homomorphisms and compactions"
    - "counting answers to existential positive queries a complexity classification"
    - "complexity of counting subgraphs only the boundedness of the vertex cover number counts"
    - "structural tractability of counting of solutions to conjunctive queries"
    - "polynomial bounds for the grid minor theorem"
    - "fixed parameter tractability definability and model checking"

Connected through hyperedge HE-2 (induced by source paper "answering conjunctive queries under updates"):
  with members:
    - "answering fo mod queries under updates on bounded degree databases"
    - "size bounds and query plans for relational joins"
    - "dynamic conjunctive queries"
    - "faster online matrix vector multiplication"
    - "unifying and strengthening hardness for dynamic problems via the online matrix vector multiplication conjecture"
    - "joins via geometric resolutions worst case and beyond"
    - "structural tractability of counting of solutions to conjunctive queries"
    - "beyond worst case analysis for joins with minesweeper"

Connected through hyperedge HE-3 (induced by source paper "the complexity of general valued csps seen from the other side"):
  with members:
    - "a dichotomy theorem for nonuniform csps"
    - "the proof of csp dichotomy conjecture"
    - "algebraic properties of valued constraint satisfaction problem"
    - "extended formulation for csp that is compact for instances of bounded treewidth"
    - "the complexity of general valued csps"
    - "the power of linear programming for valued csps"
    - "tractable optimization problems through hypergraph based structural restrictions"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"

Connected through hyperedge HE-4 (induced by source paper "answering ucqs under updates and in the presence of integrity constraints"):
  with members:
    - "dynamic conjunctive queries"
    - "answering conjunctive queries under updates"
    - "computing join queries with functional dependencies"
    - "incremental view maintenance for collection programming"
    - "structural tractability of counting of solutions to conjunctive queries"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"

Connected through hyperedge HE-5 (induced by source paper "homomorphisms are indeed a good basis for counting three fixed template dichotomy theorems for the price of one"):
  with members:
    - "the logic of counting query answers"
    - "an effective dichotomy for the counting constraint satisfaction problem"

Connected through hyperedge HE-6 (induced by source paper "counting answers to existential positive queries a complexity classification"):
  with members:
    - "the tractability frontier of graph like first order query sets"
    - "structural tractability of counting of solutions to conjunctive queries"
    - "one hierarchy spawns another graph deconstructions and the complexity classification of conjunctive queries"
    - "on the complexity of existential positive queries"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"

Connected through hyperedge HE-7 (induced by source paper "faq questions asked frequently"):
  with members:
    - "size bounds and query plans for relational joins"
    - "constraint solving via fractional edge covers"
    - "what do shannon type inequalities submodular width and disjunctive datalog have to do with one another"
    - "computing join queries with functional dependencies"
    - "general and fractional hypertree decompositions hard and easy cases"
    - "join processing for graph patterns an old dog with new tricks"
    - "emptyheaded boolean algebra based graph processing"
    - "joins via geometric resolutions worst case and beyond"

Connected through hyperedge HE-8 (induced by source paper "the logic of counting query answers"):
  with members:
    - "counting answers to existential positive queries a complexity classification"
    - "the tractability frontier of graph like first order query sets"
    - "structural tractability of counting of solutions to conjunctive queries"
    - "one hierarchy spawns another graph deconstructions and the complexity classification of conjunctive queries"
    - "tree width for first order formulae"
    - "on the complexity of existential positive queries"

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.CC(Computational Complexity)