human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "parameterized approximation algorithms for directed steiner network problems"):
  Abstract: (Shortened abstract below, see paper for full abstract) #R##N#Given an edge-weighted directed graph $G=(V,E)$ and a set of $k$ terminal pairs $\{(s_i, t_i)\}_{i=1}^{k}$, the objective of the \pname{Directed Steiner Network (DSN)} problem is to compute the cheapest subgraph $N$ of $G$ such that there is an $s_i\to t_i$ path in $N$ for each $i\in [k]$. This problem is notoriously hard: there is no polytime $O(2^{\log^{1-\eps}n})$-approximation~[Dodis \& Khanna, \emph{STOC}~'99], and it is W[1]-hard~[Guo~et~al., \emph{SIDMA}~'11] for the well-studied parameter $k$. One option to circumvent these hardness results is to obtain a \emph{parameterized approximation}. Our first result is the following: #R##N#- Under Gap-ETH there is no $k^{o(1)}$-approximation for \pname{DSN} in $f(k)\cdot n^{O(1)}$ time for any function~$f$. #R##N#Given our results above, the question we explore in this paper is: can we obtain faster algorithms or better approximation ratios for other special cases of \pname{DSN} when parameterizing by $k$? #R##N#A well-studied special case of \pname{DSN} is the \pname{Strongly Connected Steiner Subgraph (SCSS)} problem, where the goal is to find the cheapest subgraph of $G$, which pairwise connects all $k$ given terminals. We show the following #R##N#- Under Gap-ETH no $(2-\eps)$-approximation can be computed in $f(k)\cdot n^{O(1)}$ time, for any function~$f$. This shows that the $2$-approximation in $2^k\polyn$ time observed in~[Chitnis~et~al., \emph{IPEC}~2013] is optimal. #R##N#Next we consider \dsn and \scss when the input graph is \emph{bidirected}, i.e., for every edge $uv$ the reverse edge exists and has the same weight. We call the respective problems \bidsn and \biscss and show: #R##N#- \biscss is NP-hard, but there is a \smash{$2^{O(2^{k^2-k})}\polyn$} time algorithm. #R##N#- In contrast, \bidsn is W[1]-hard parameterized by $k$.

Includes members:
  Member "complexity of the steiner network problem with respect to the number of terminals":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "tight bounds for planar strongly connected steiner subgraph with fixed number of terminals and extensions")
  Member "eth hardness of approximating 2 csps and directed steiner network":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "tight running time lower bounds for strong inapproximability of maximum k coverage unique set cover and related problems via t wise agreement testing theorem")
  Member "the complexity landscape of fixed parameter directed steiner network problems":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "a relaxation of the directed disjoint paths problem a global congestion metric helps")
  Member "from gap eth to fpt inapproximability clique dominating set and more":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "parameterized inapproximability for steiner orientation by gap amplification")
  Member "on subexponential parameterized algorithms for steiner tree and directed subset tsp on planar graphs":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "tight bounds for planar strongly connected steiner subgraph with fixed number of terminals and extensions")
  Member "parameterized complexity and approximability of directed odd cycle transversal":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "multi budgeted directed cuts")
  Member "subexponential parameterized algorithms for planar and apex minor free graphs via low treewidth pattern covering":
    also connected through other hyperedges:
      - Hyperedge HE-7 (induced by source paper "tight bounds for planar strongly connected steiner subgraph with fixed number of terminals and extensions")
  Member "almost polynomial ratio eth hardness of approximating densest k subgraph":
    also connected through other hyperedges:
      - Hyperedge HE-8 (induced by source paper "optimizing item and subgroup configurations for social aware vr shopping")

Question: Please tell me which class the source paper 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)