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: "on the expressive power of planar perfect matching and permanents of bounded treewidth matrices"
  Abstract: Valiant introduced some 25 years ago an algebraic model of computation along with the complexity classes VP and VNP, which can be viewed as analogues of the classical classes P and NP. They are defined using non-uniform sequences of arithmetic circuits and provides a framework to study the complexity for sequences of polynomials. Prominent examples of difficult (that is, VNP-complete) problems in this model includes the permanent and hamiltonian polynomials. While the permanent and hamiltonian polynomials in general are difficult to evaluate, there have been research on which special cases of these polynomials admits efficient evaluation. For instance, Barvinok has shown that if the underlying matrix has bounded rank, both the permanent and the hamiltonian polynomials can be evaluated in polynomial time, and thus are in VP. Courcelle, Makowsky and Rotics have shown that for matrices of bounded treewidth several difficult problems (including evaluating the permanent and hamiltonian polynomials) can be solved efficiently. An earlier result of this flavour is Kasteleyn's theorem which states that the sum of weights of perfect matchings of a planar graph can be computed in polynomial time, and thus is in VP also. For general graphs this problem is VNP-complete. In this paper we investigate the expressive power of the above results. We show that the permanent and hamiltonian polynomials for matrices of bounded treewidth both are equivalent to arithmetic formulas. Also, arithmetic weakly skew circuits are shown to be equivalent to the sum of weights of perfect matchings of planar graphs.

Connected through hyperedge HE-1 (induced by source paper "parameterized valiant s classes"):
  with members:
    - "a fixed parameter perspective on bis"
    - "homomorphisms are a good basis for counting small subgraphs"
    - "counting restricted homomorphisms via m obius inversion over matroid lattices"
    - "on the relative power of reduction notions in arithmetic circuit complexity"
    - "some complete and intermediate polynomials in algebraic complexity theory"
    - "algebraic complexity classes"
    - "complexity of counting subgraphs only the boundedness of the vertex cover number counts"
    - "paradigms for parameterized enumeration"

Connected through hyperedge HE-2 (induced by source paper "an efficient tree decomposition method for permanents and mixed discriminants"):
  with members:
    - "bounded treewidth and space efficient linear algebra"
    - "the bethe permanent of a nonnegative matrix"
    - "efficient computation of the permanent of block factorizable matrices"
    - "strategy iteration is strongly polynomial for 2 player turn based stochastic games with a constant discount factor"
    - "belief propagation and loop calculus for the permanent of a non negative matrix"
    - "most tensor problems are np hard"

Connected through hyperedge HE-3 (induced by source paper "new algorithms and hard instances for non commutative computation"):
  with members:
    - "progress on polynomial identity testing ii"
    - "almost settling the hardness of noncommutative determinant"
    - "monomials in arithmetic circuits complete problems in the counting hierarchy"
    - "arithmetic circuits and the hadamard product of polynomials"
    - "on the expressive power of permanents and perfect matchings of matrices of bounded pathwidth cliquewidth"
    - "new results on noncommutative and commutative polynomial identity testing"

Connected through hyperedge HE-4 (induced by source paper "log space algorithms for paths and matchings in k trees"):
  with members:
    - "deterministically isolating a perfect matching in bipartite planar graphs"
    - "longest paths in planar dags in unambiguous logspace"

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)