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 directed grid theorem"
  Abstract: The grid theorem, originally proved by Robertson and Seymour in Graph Minors V in 1986, is one of the most central results in the study of graph minors. It has found numerous applications in algorithmic graph structure theory, for instance in bidimensionality theory, and it is the basis for several other structure theorems developed in the graph minors project. #R##N#In the mid-90s, Reed and Johnson, Robertson, Seymour and Thomas (see [Reed 97, Johnson, Robertson, Seymour, Thomas 01]), independently, conjectured an analogous theorem for directed graphs, i.e. the existence of a function f : N -> N such that every digraph of directed tree-width at least f(k) contains a directed grid of order k. In an unpublished manuscript from 2001, Johnson, Robertson, Seymour and Thomas give a proof of this conjecture for planar digraphs. But for over a decade, this was the most general case proved for the Reed, Johnson, Robertson, Seymour and Thomas conjecture. #R##N#Only very recently, this result has been extended to all classes of digraphs excluding a fixed undirected graph as a minor (see [Kawarabayashi, Kreutzer 14]). In this paper, nearly two decades after the conjecture was made, we are finally able to confirm the Reed, Johnson, Robertson, Seymour and Thomas conjecture in full generality and to prove the directed grid theorem. #R##N#As consequence of our results we are able to improve results in Reed et al. in 1996 [Reed, Robertson, Seymour, Thomas 96] (see also [Open Problem Garden]) on disjoint cycles of length at least l and in [Kawarabayashi, Kobayashi, Kreutzer 14] on quarter-integral disjoint paths. We expect many more algorithmic results to follow from the grid theorem.

Connected through hyperedge HE-1 (induced by source paper "hitting long directed cycles is fixed parameter tractable"):
  with members:
    - "reducing cmso model checking to highly connected graphs"
    - "dag width and circumference of digraphs"
    - "on feedback vertex set new measure and new structures"
    - "a randomized algorithm for long directed cycle"
    - "representative sets of product families"
    - "representative families a unified tradeoff based approach"
    - "faster deterministic feedback vertex set"
    - "directed subset feedback vertex set is fixed parameter tractable"

Connected through hyperedge HE-2 (induced by source paper "a relaxation of the directed disjoint paths problem a global congestion metric helps"):
  with members:
    - "dual parameterization of weighted coloring"
    - "the complexity landscape of fixed parameter directed steiner network problems"
    - "routing with congestion in acyclic digraphs"
    - "network sparsification for steiner problems on planar and bounded genus graphs"
    - "the planar directed k vertex disjoint paths problem is fixed parameter tractable"
    - "fixed parameter tractability of multicut in directed acyclic graphs"
    - "parameterized complexity of directed steiner tree on sparse graphs"
    - "fixed parameter tractability of directed multiway cut parameterized by the size of the cutset"

Connected through hyperedge HE-3 (induced by source paper "parametrised algorithms for directed modular width"):
  with members:
    - "on directed feedback vertex set parameterized by treewidth"
    - "an algorithmic metatheorem for directed treewidth"
    - "parameterized algorithms for modular width"
    - "the planar directed k vertex disjoint paths problem is fixed parameter tractable"
    - "finding an induced subdivision of a digraph"
    - "finding topological subgraphs is fixed parameter tractable"

Connected through hyperedge HE-4 (induced by source paper "packing directed circuits quarter integrally"):
  with members:
    - "routing symmetric demands in directed minor free graphs with constant congestion"
    - "large treewidth graph decompositions and applications"
    - "polynomial bounds for the grid minor theorem"
    - "a polylogarithimic approximation algorithm for edge disjoint paths with congestion 2"

Connected through hyperedge HE-5 (induced by source paper "finding detours is fixed parameter tractable"):
  with members:
    - "improved bounds for the excluded grid theorem"
    - "mixing color coding related techniques"
    - "polynomial bounds for the grid minor theorem"
    - "vertex cover problem parameterized above and below tight bounds"
    - "solving max r sat above a tight lower bound"

Connected through hyperedge HE-6 (induced by source paper "k distinct in and out branchings in digraphs"):
  with members:
    - "spanning directed trees with many leaves"

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)