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: "an fpt algorithm for directed spanning k leaf"
  Abstract: An out-branching of a directed graph is a rooted spanning tree with all arcs directed outwards from the root. We consider the problem of deciding whether a given directed graph D has an out-branching with at least k leaves (Directed Spanning k-Leaf). We prove that this problem is fixed parameter tractable, when k is chosen as the parameter. Previously this was only known for restricted classes of directed graphs. #R##N#The main new ingredient in our approach is a lemma that shows that given a locally optimal out-branching of a directed graph in which every arc is part of at least one out-branching, either an out-branching with at least k leaves exists, or a path decomposition with width O(k^3) can be found. This enables a dynamic programming based algorithm of running time 2^{O(k^3 \log k)} n^{O(1)}, where n=|V(D)|.

Connected through hyperedge HE-1 (induced by source paper "on finding directed trees with many leaves"):
  with members:
    - "kernel s for problems with no kernel on out trees with many leaves"
    - "spanning directed trees with many leaves"
    - "parameterized algorithms for directed maximum leaf problems"

Connected through hyperedge HE-2 (induced by source paper "minimum leaf out branching and related problems"):
  with members:
    - "algorithm for finding k vertex out trees and its application to k internal out branching problem"
    - "parameterized algorithms for directed maximum leaf problems"
    - "better algorithms and bounds for directed maximum leaf problems"
    - "fixed parameter complexity of minimum profile problems"
    - "the linear arrangement problem parameterized above guaranteed value"

Connected through hyperedge HE-3 (induced by source paper "fpt algorithms and kernels for the directed k leaf problem"):
  with members:
    - "spanning directed trees with many leaves"
    - "parameterized algorithms for directed maximum leaf problems"
    - "better algorithms and bounds for directed maximum leaf problems"

Connected through hyperedge HE-4 (induced by source paper "tight bounds and faster algorithms for directed max leaf problems"):
  with members:
    - "parameterized algorithms for directed maximum leaf problems"
    - "better algorithms and bounds for directed maximum leaf problems"

Connected through hyperedge HE-5 (induced by source paper "spanning directed trees with many leaves"):
  with members:
    - "parameterized algorithms for directed maximum leaf problems"
    - "better algorithms and bounds for directed maximum leaf 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.DS(Data Structures and Algorithms)