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: "directed steiner tree and the lasserre hierarchy"
  Abstract: The goal for the Directed Steiner Tree problem is to find a minimum cost tree in a directed graph G=(V,E) that connects all terminals X to a given root r. It is well known that modulo a logarithmic factor it suffices to consider acyclic graphs where the nodes are arranged in L <= log |X| levels. Unfortunately the natural LP formulation has a |X|^(1/2) integrality gap already for 5 levels. We show that for every L, the O(L)-round Lasserre Strengthening of this LP has integrality gap O(L log |X|). This provides a polynomial time |X|^{epsilon}-approximation and a O(log^3 |X|) approximation in O(n^{log |X|) time, matching the best known approximation guarantee obtained by a greedy algorithm of Charikar et al.

Connected through hyperedge HE-1 (induced by source paper "polylogarithmic approximation algorithm for k connected directed steiner tree on quasi bipartite graphs"):
  with members:
    - "a quasi polynomial algorithm for submodular tree orienteering in directed graphs"
    - "a logarithmic integrality gap bound for directed steiner tree in quasi bipartite graphs"
    - "approximating directed steiner problems via tree embedding"
    - "analytical approach to parallel repetition"
    - "parameters of two prover one round game and the hardness of connectivity problems"
    - "an improved approximation algorithm for the minimum cost subset k connected subgraph problem"
    - "approximating subset k connectivity problems"
    - "an o k 3 log n approximation algorithm for vertex connectivity survivable network design"

Connected through hyperedge HE-2 (induced by source paper "lasserre integrality gaps for graph spanners and related problems"):
  with members:
    - "characterizing demand graphs for fixed parameter shallow light steiner network"
    - "approximating spanners and directed steiner forest upper and lower bounds"
    - "parallel metric tree embedding based on an algebraic view on moore bellman ford"
    - "everywhere sparse spanners via dense subgraphs"
    - "label cover instances with large girth and the hardness of approximating basic k spanner"
    - "rounding semidefinite programming hierarchies via global correlation"
    - "fault tolerant spanners better and simpler"
    - "directed spanners via flow based linear programs"

Connected through hyperedge HE-3 (induced by source paper "tight approximation for variants of directed steiner tree via state tree decomposition and linear programming rounding"):
  with members:
    - "a quasi polynomial algorithm for submodular tree orienteering in directed graphs"
    - "online weighted degree bounded steiner networks via novel online mixed packing covering"
    - "online buy at bulk network design"
    - "approximating directed steiner problems via tree embedding"
    - "bicriteria network design problems"

Connected through hyperedge HE-4 (induced by source paper "a quasi polynomial algorithm for submodular tree orienteering in directed graphs"):
  with members:
    - "a constant factor approximation algorithm for the asymmetric traveling salesman problem"

Connected through hyperedge HE-5 (induced by source paper "surviving in directed graphs a polylogarithmic approximation for two connected directed steiner tree"):
  with members:
    - "parameters of two prover one round game and the hardness of connectivity problems"
    - "iterative rounding approximation algorithms for degree bounded node connectivity network design"
    - "approximating minimum cost k node connected subgraphs via independence free graphs"
    - "an improved approximation algorithm for the minimum cost subset k connected subgraph problem"
    - "approximating subset k connectivity problems"

Connected through hyperedge HE-6 (induced by source paper "approximating unweighted tree augmentation via lift and project part 0 1 8 e approximation for unweighted tap"):
  with members:
    - "sum of squares proofs and the quest toward optimal algorithms"
    - "new inapproximability bounds for tsp"

Connected through hyperedge HE-7 (induced by source paper "a logarithmic integrality gap bound for directed steiner tree in quasi bipartite graphs"):
  with members:
    - "analytical approach to parallel repetition"

Connected through hyperedge HE-8 (induced by source paper "approximating unweighted tree augmentation via lift and project part i stemless tap"):
  with members:
    - "approximating unweighted tree augmentation via lift and project part 0 1 8 e approximation for unweighted tap"
    - "a 1 75 lp approximation for the tree augmentation problem"
    - "a simplified 1 5 approximation algorithm for augmenting edge connectivity of a graph from 1 to 2"
    - "integrality gaps of linear and semi definite programming relaxations for knapsack"

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)