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: "functional clones and expressibility of partition functions"
  Abstract: We study functional clones, which are sets of non-negative pseudo-Boolean functions closed under (essentially) multiplication, summation and limits. Functional clones naturally form a lattice under set inclusion and are closely related to counting Constraint Satisfaction Problems (CSPs). We identify a sublattice of interesting functional clones and investigate the relationships and properties of the functional clones in this sublattice.

Connected through hyperedge HE-1 (induced by source paper "counting perfect matchings and the eight vertex model"):
  with members:
    - "approximability of the six vertex model"
    - "approximating holant problems by winding"
    - "inapproximability of the tutte polynomial"

Connected through hyperedge HE-2 (induced by source paper "holant clones and the approximability of conservative holant problems"):
  with members:
    - "boolean approximate counting csps with weak conservativity and implications for ferromagnetic two spin"
    - "inapproximability of the independent set polynomial in the complex plane"
    - "the complexity of holant problems over boolean domain with non negative weights"
    - "the complexity of approximating conservative counting csps"
    - "the complexity of conservative valued csps"
    - "the expressibility of functions on the boolean domain with applications to counting csps"
    - "complexity of counting csp with complex weights"
    - "approximation complexity of complex weighted degree two counting constraint satisfaction problems"

Connected through hyperedge HE-3 (induced by source paper "boolean approximate counting csps with weak conservativity and implications for ferromagnetic two spin"):
  with members:
    - "inapproximability of the partition function for the antiferromagnetic ising and hard core models"
    - "the complexity of approximating conservative counting csps"
    - "the complexity of ferromagnetic two spin systems with external fields"
    - "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"

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.DM(Discrete Mathematics)