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: "effectiveness of structural restrictions for hybrid csps"
  Abstract: Constraint Satisfaction Problem (CSP) is a fundamental algorithmic problem that appears in many areas of Computer Science. It can be equivalently stated as computing a homomorphism $\mbox{$\bR \rightarrow \bGamma$}$ between two relational structures, e.g.\ between two directed graphs. Analyzing its complexity has been a prominent research direction, especially for {\em fixed template CSPs} in which the right side $\bGamma$ is fixed and the left side $\bR$ is unconstrained. #R##N#Far fewer results are known for the {\em hybrid} setting that restricts both sides simultaneously. It assumes that $\bR$ belongs to a certain class of relational structures (called a {\em structural restriction} in this paper). We study which structural restrictions are {\em effective}, i.e.\ there exists a fixed template $\bGamma$ (from a certain class of languages) for which the problem is tractable when $\bR$ is restricted, and NP-hard otherwise. We provide a characterization for structural restrictions that are {\em closed under inverse homomorphisms}. The criterion is based on the {\em chromatic number} of a relational structure defined in this paper; it generalizes the standard chromatic number of a graph. #R##N#As our main tool, we use the algebraic machinery developed for fixed template CSPs. To apply it to our case, we introduce a new construction called a "lifted language." We also give a characterization for structural restrictions corresponding to minor-closed families of graphs, extend results to certain Valued CSPs (namely conservative valued languages), and state implications for CSPs with ordered variables, (valued) CSPs on structures with large girth, and for the maximum weight independent set problem on some restricted families of graphs including graphs with large girth.

Connected through hyperedge HE-1 (induced by source paper "on planar valued csps"):
  with members:
    - "the power of sherali adams relaxations for general valued csps"
    - "even delta matroids and the complexity of planar boolean csps"
    - "the complexity of finite valued csps"
    - "a galois connection for weighted relational clones of infinite size"
    - "necessary conditions for tractability of valued csps"
    - "hybrid v csps and algebraic reductions"
    - "algebraic properties of valued constraint satisfaction problem"
    - "the complexity of general valued csps"

Connected through hyperedge HE-2 (induced by source paper "even delta matroids and the complexity of planar boolean csps"):
  with members:
    - "a dichotomy theorem for nonuniform csps"
    - "the proof of csp dichotomy conjecture"
    - "the complexity of finite valued csps"
    - "algebraic properties of valued constraint satisfaction problem"
    - "the complexity of general valued csps"
    - "the complexity of conservative valued csps"
    - "approximate constraint satisfaction requires large lp relaxations"
    - "hybrid tractability of valued constraint problems"

Connected through hyperedge HE-3 (induced by source paper "the power of arc consistency for csps defined by partially ordered forbidden patterns"):
  with members:
    - "hybrid v csps and algebraic reductions"
    - "tractable hypergraph properties for constraint satisfaction and conjunctive queries"
    - "generalized majority minority operations are tractable"

Connected through hyperedge HE-4 (induced by source paper "the complexity of general valued csps"):
  with members:
    - "the power of sherali adams relaxations for general valued csps"
    - "combinatorial optimization algorithms via polymorphisms"
    - "a galois connection for valued constraint languages of infinite size"
    - "algebraic properties of valued constraint satisfaction problem"
    - "local distribution and the symmetry gap approximability of multiway partitioning problems"
    - "sherali adams relaxations for valued csps"
    - "robustly solvable constraint satisfaction problems"
    - "an algebraic theory of complexity for discrete optimization"

Connected through hyperedge HE-5 (induced by source paper "hybrid v csps and algebraic reductions"):
  with members:
    - "algebraic properties of valued constraint satisfaction problem"
    - "the complexity of general valued csps"
    - "sherali adams relaxations for valued csps"
    - "the complexity of conservative valued csps"
    - "on the reduction of the csp dichotomy conjecture to digraphs"
    - "hybrid tractability of valued constraint problems"

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)