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 signed graph and edge coloured graph homomorphisms"
  Abstract: Abstract   We study homomorphism problems of signed graphs from a computational point of view. A signed graph     (  G  ,  Σ  )     is a graph    G    where each edge is given a sign, positive or negative;    Σ  ⊆  E   (  G  )     denotes the set of negative edges. Thus,     (  G  ,  Σ  )     is a    2   -edge-coloured graph with the property that the edge-colours,     {  +  ,  −  }    , form a group under multiplication. Central to the study of signed graphs is the operation of switching at a vertex, that results in changing the sign of each incident edge. We study two types of homomorphisms of a signed graph     (  G  ,  Σ  )     to a signed graph     (  H  ,  Π  )    : ec-homomorphisms and s-homomorphisms. Each is a standard graph homomorphism of    G    to    H    with some additional constraint. In the former, edge-signs are preserved. In the latter, edge-signs are preserved after the switching operation has been applied to a subset of vertices of    G   .  We prove a dichotomy theorem for s-homomorphism problems for a large class of (fixed) target signed graphs     (  H  ,  Π  )    . Specifically, as long as     (  H  ,  Π  )     does not contain a negative (respectively a positive) loop, the problem is polynomial-time solvable if the core of     (  H  ,  Π  )     has at most two edges, and is NP-complete otherwise. (Note that this covers all simple signed graphs.) The same dichotomy holds if     (  H  ,  Π  )     has no negative digons, and we conjecture that it holds always. In our proofs, we reduce s-homomorphism problems to certain ec-homomorphism problems, for which we are able to show a dichotomy. In contrast, we prove that a dichotomy theorem for ec-homomorphism problems (even when restricted to bipartite target signed graphs) would settle the dichotomy conjecture of Feder and Vardi.

Connected through hyperedge HE-1 (induced by source paper "the complexity of tropical graph homomorphisms"):
  with members:
    - "dichotomy for digraph homomorphism problems two algorithms"

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)