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: "lp rounding algorithms for facility location problems"
  Abstract: We study LP-rounding approximation algorithms for metric uncapacitated facility-location problems. We first give a new analysis for the algorithm of Chudak and Shmoys, which differs from the analysis of Byrka and Aardal in that now we do not need any bound based on the solution to the dual LP program. Besides obtaining the optimal bifactor approximation as do Byrka and Aardal, we can now also show that the algorithm with scaling parameter equaling 1.58 is, in fact, an 1.58-approximation algorithm. More importantly, we suggest an approach based on additional randomization and analyses such as ours, which could achieve or approach the conjectured optimal 1.46...--approximation for this basic problem. #R##N#Next, using essentially the same techniques, we obtain improved approximation algorithms in the 2-stage stochastic variant of the problem, where we must open a subset of facilities having only stochastic information about the future demand from the clients. For this problem we obtain a 2.2975-approximation algorithm in the standard setting, and a 2.4957-approximation in the more restricted, per-scenario setting. #R##N#We then study robust fault-tolerant facility location, introduced by Chechik and Peleg: solutions here are designed to provide low connection cost in case of failure of up to $k$ facilities. Chechik and Peleg gave a 6.5-approximation algorithm for $k=1$ and a ($7.5k + 1.5$)-approximation algorithm for general $k$. We improve this to an LP-rounding $(k+5+4/k)$-approximation algorithm. We also observe that in case of oblivious failures the expected approximation ratio can be reduced to $k + 1.5$, and that the integrality gap of the natural LP-relaxation of the problem is at least $k + 1$.

Connected through hyperedge HE-1 (induced by source paper "robust network function virtualization"):
  with members:
    - "integrated nfv sdn architectures a systematic literature review"
    - "a scalable approach for service chain mapping with multiple sc instances in a wide area network"
    - "shortest path and maximum flow problems under service function chaining constraints"
    - "service function chaining resource allocation a survey"
    - "an approximation algorithm for path computation and function placement in sdns"
    - "service chain and virtual network embeddings approximations using randomized rounding"
    - "network function virtualization state of the art and research challenges"
    - "fronthaul constrained cloud radio access networks insights and challenges"

Connected through hyperedge HE-2 (induced by source paper "an attempt to design a better algorithm for the uncapacitated facility location problem"):
  with members:
    - "an optimal bifactor approximation algorithm for the metric uncapacitated facility location problem"
    - "greedy facility location algorithms analyzed using dual fitting with factor revealing lp"

Connected through hyperedge HE-3 (induced by source paper "improved approximation algorithm for fault tolerant facility placement"):
  with members:
    - "analytical approach to parallel repetition"
    - "lp rounding algorithms for the fault tolerant facility placement problem"
    - "fault tolerant facility location a randomized dependent lp rounding algorithm"
    - "an optimal bifactor approximation algorithm for the metric uncapacitated facility location problem"

Connected through hyperedge HE-4 (induced by source paper "improved approximation algorithm for k level ufl with penalties a simplistic view on randomizing the scaling parameter"):
  with members:
    - "an optimal bifactor approximation algorithm for the metric uncapacitated facility location problem"
    - "greedy facility location algorithms analyzed using dual fitting with factor revealing lp"

Connected through hyperedge HE-5 (induced by source paper "lp rounding algorithms for the fault tolerant facility placement problem"):
  with members:
    - "a constant factor approximation algorithm for fault tolerant k median"
    - "improved approximation algorithm for fault tolerant facility placement"
    - "unconstrained and constrained fault tolerant resource allocation"
    - "fault tolerant facility location a randomized dependent lp rounding algorithm"
    - "an optimal bifactor approximation algorithm for the metric uncapacitated facility location problem"
    - "greedy facility location algorithms analyzed using dual fitting with factor revealing lp"

Connected through hyperedge HE-6 (induced by source paper "approximating soft capacitated facility location problem with uncertainty"):
  with members:
    - "fault tolerant facility location a randomized dependent lp rounding algorithm"
    - "robust fault tolerant uncapacitated facility location"

Connected through hyperedge HE-7 (induced by source paper "constrained fault tolerant resource allocation"):
  with members:
    - "lp rounding algorithms for the fault tolerant facility placement problem"

Connected through hyperedge HE-8 (induced by source paper "a systematic approach to bound factor revealing lps and its application to the metric and squared metric facility location problems"):
  with members:
    - "squared metric facility location problem"
    - "an optimal bifactor approximation algorithm for the metric uncapacitated facility location problem"
    - "greedy facility location algorithms analyzed using dual fitting with factor revealing lp"

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)