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: "breaching the 2 approximation barrier for connectivity augmentation a reduction to steiner tree"
  Abstract: The basic goal of survivable network design is to build a cheap network that maintains the connectivity between given sets of nodes despite the failure of a few edges/nodes. The Connectivity Augmentation Problem (CAP) is arguably one of the most basic problems in this area: given a k(edge)-connected graph G and a set of extra edges (links), select a minimum cardinality subset A of links such that adding A to G increases its edge connectivity to k + 1. Intuitively, one wants to make an existing network more reliable by augmenting it with extra edges. The best known approximation factor for this NP-hard problem is 2, and this can be achieved with multiple approaches (the first such result is in [Frederickson and Jaja'81]). #R##N#It is known [Dinitz et al.'76] that CAP can be reduced to the case k = 1, a.k.a. the Tree Augmentation Problem (TAP), for odd k, and to the case k = 2, a.k.a. the Cactus Augmentation Problem (CacAP), for even k. Several better than 2 approximation algorithms are known for TAP, culminating with a recent 1.458 approximation [Grandoni et al.'18]. However, for CacAP the best known approximation is 2. #R##N#In this paper we breach the 2 approximation barrier for CacAP, hence for CAP, by presenting a polynomial-time $2 ln(4) - 967 + \epsilon < 1.91$ approximation. Previous approaches exploit properties of TAP that do not seem to generalize to CacAP. We instead use a reduction to the Steiner tree problem which was previously used in parameterized algorithms [Basavaraju et al.'14]. This reduction is not approximation preserving, and using the current best approximation factor for Steiner tree [Byrka et al.'13] as a black-box would not be good enough to improve on 2. To achieve the latter goal, we "open the box" and exploit the specific properties of the instances of Steiner tree arising from CacAP.

Connected through hyperedge HE-1 (induced by source paper "2 node connectivity network design"):
  with members:
    - "approximating k connected m dominating sets"
    - "improved approximation for tree augmentation saving by rewiring"
    - "approximation algorithm for minimum weight fault tolerant virtual backbone in unit disk graphs"
    - "on the tree augmentation problem"
    - "a simplified 1 5 approximation algorithm for augmenting edge connectivity of a graph from 1 to 2"
    - "improved approximation algorithms for budgeted node weighted steiner problems"
    - "nearly tight low stretch spanning trees"
    - "lower stretch spanning trees"

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)