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: "the complexity of ferromagnetic two spin systems with external fields"
  Abstract: We study the approximability of computing the partition function for ferromagnetic two-state spin systems. The remarkable algorithm by Jerrum and Sinclair showed that there is a fully polynomial-time randomized approximation scheme (FPRAS) for the special ferromagnetic Ising model with any given uniform external field. Later, Goldberg and Jerrum proved that it is #BIS-hard for Ising model if we allow inconsistent external fields on different nodes. In contrast to these two results, we prove that for any ferromagnetic two-state spin systems except the Ising model, there exists a threshold for external fields beyond which the problem is #BIS-hard, even if the external field is uniform.

Connected through hyperedge HE-1 (induced by source paper "boolean approximate counting csps with weak conservativity and implications for ferromagnetic two spin"):
  with members:
    - "functional clones and expressibility of partition functions"
    - "inapproximability of the partition function for the antiferromagnetic ising and hard core models"
    - "the complexity of approximating conservative counting csps"
    - "the expressibility of functions on the boolean domain with applications to counting csps"
    - "approximating the tutte polynomial of a binary matroid and other related combinatorial polynomials"
    - "approximation algorithms for two state anti ferromagnetic spin systems on bounded degree graphs"
    - "correlation decay up to uniqueness in spin systems"
    - "from holant to csp and back dichotomy for holant c problems"

Connected through hyperedge HE-2 (induced by source paper "bis hardness for 2 spin systems on bipartite bounded degree graphs in the tree non uniqueness region"):
  with members:
    - "inapproximability of the partition function for the antiferromagnetic ising and hard core models"
    - "the complexity of approximating conservative counting csps"
    - "approximating the partition function of planar two state spin systems"
    - "the expressibility of functions on the boolean domain with applications to counting csps"
    - "inapproximability for antiferromagnetic spin systems in the tree non uniqueness region"
    - "inapproximability after uniqueness phase transition in two spin systems"
    - "approximating the partition function of the ferromagnetic potts model"
    - "approximation algorithms for two state anti ferromagnetic spin systems on bounded degree graphs"

Connected through hyperedge HE-3 (induced by source paper "fptas for bis with degree bounds on one side"):
  with members:
    - "a simple fptas for counting edge covers"
    - "spatial mixing and the connective constant optimal bounds"
    - "the expressibility of functions on the boolean domain with applications to counting csps"
    - "fptas for counting monotone cnf"
    - "spatial mixing and approximation algorithms for graphs with bounded connective constant"
    - "the complexity of approximately counting stable roommate assignments"
    - "approximating the partition function of the ferromagnetic potts model"
    - "approximation algorithms for two state anti ferromagnetic spin systems on bounded degree graphs"

Connected through hyperedge HE-4 (induced by source paper "uniqueness spatial mixing and approximation for ferromagnetic 2 spin systems"):
  with members:
    - "bis hardness for 2 spin systems on bipartite bounded degree graphs in the tree non uniqueness region"
    - "inapproximability of the partition function for the antiferromagnetic ising and hard core models"
    - "spatial mixing and the connective constant optimal bounds"
    - "approximation algorithms for two state anti ferromagnetic spin systems on bounded degree graphs"
    - "correlation decay up to uniqueness in spin systems"
    - "approximate counting via correlation decay in spin systems"
    - "computational transition at the uniqueness threshold"
    - "approximating partition functions of two state spin systems"

Connected through hyperedge HE-5 (induced by source paper "ferromagnetic potts model refined bis hardness and related results"):
  with members:
    - "the condensation phase transition in random graph coloring"
    - "the complexity of approximating conservative counting csps"
    - "the expressibility of functions on the boolean domain with applications to counting csps"
    - "approximating the partition function of the ferromagnetic potts model"
    - "correlation decay up to uniqueness in spin systems"
    - "computational transition at the uniqueness threshold"

Connected through hyperedge HE-6 (induced by source paper "inapproximability for antiferromagnetic spin systems in the tree non uniqueness region"):
  with members:
    - "inapproximability of the partition function for the antiferromagnetic ising and hard core models"
    - "approximation algorithms for two state anti ferromagnetic spin systems on bounded degree graphs"
    - "correlation decay up to uniqueness in spin systems"
    - "approximate counting via correlation decay in spin systems"
    - "computational transition at the uniqueness threshold"
    - "a constructive proof of the general lovasz local lemma"

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)