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: "improved approximation guarantees for lower bounded facility location"
  Abstract: We consider the {\em lower-bounded facility location} (\lbfl) problem (also sometimes called {\em load-balanced facility location}), which is a generalization of {\em uncapacitated facility location} (\ufl), where each open facility is required to serve a certain {\em minimum} amount of demand. More formally, an instance $\I$ of \lbfl is specified by a set $\F$ of facilities with facility-opening costs $\{f_i\}$, a set $\D$ of clients, and connection costs $\{c_{ij}\}$ specifying the cost of assigning a client $j$ to a facility $i$, where the $c_{ij}$s form a metric. A feasible solution specifies a subset $F$ of facilities to open, and assigns each client $j$ to an open facility $i(j)\in F$ so that each open facility serves {\em at least $M$ clients}, where $M$ is an input parameter. The cost of such a solution is $\sum_{i\in F}f_i+\sum_j c_{i(j)j}$, and the goal is to find a feasible solution of minimum cost. The current best approximation ratio for \lbfl is 448 \cite{Svitkina08}. We substantially advance the state-of-the-art for \lbfl by devising an approximation algorithm for \lbfl that achieves a significantly-improved approximation guarantee of 82.6. Our improvement comes from a variety of ideas in algorithm design and analysis, which also yield new insights into \lbfl.

Connected through hyperedge HE-1 (induced by source paper "fair algorithms for clustering"):
  with members:
    - "tight fpt approximations for k median and k means"
    - "scalable fair clustering"
    - "on the cost of essentially fair clusterings"
    - "privacy preserving clustering with constraints"
    - "constant factor fpt approximation for capacitated k median"
    - "a unified framework for clustering constrained data without locality property"
    - "fair clustering through fairlets"
    - "generalized center problems with outliers"

Connected through hyperedge HE-2 (induced by source paper "faster balanced clusterings in high dimension"):
  with members:
    - "privacy preserving clustering with constraints"
    - "balanced k center clustering when k is a constant"
    - "capacitated center problems with two sided bounds and outliers"
    - "approximation algorithms for clustering problems with lower bounds and outliers"
    - "local search yields a ptas for k means in doubling metrics"
    - "local search yields approximation schemes for k means and k median in euclidean and minor free metrics"
    - "distributed balanced partitioning via linear embedding"
    - "data driven resource allocation for distributed learning"

Connected through hyperedge HE-3 (induced by source paper "on facility location with general lower bounds"):
  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-4 (induced by source paper "approximation algorithms for clustering problems with lower bounds and outliers"):
  with members:
    - "constant factor approximation for capacitated k center with outliers"
    - "an improved approximation for k median and positive correlation in budgeted optimization"
    - "fast clustering with lower bounds no customer too far no shop too small"
    - "approximating k median via pseudo approximation"

Connected through hyperedge HE-5 (induced by source paper "integrality gaps for strengthened lp relaxations of capacitated and lower bounded facility location"):
  with members:
    - "approximating k median via pseudo approximation"
    - "approximation limits of linear programs beyond hierarchies"
    - "lp rounding for k centers with non uniform hard capacities"
    - "polynomial integrality gaps for strong sdp relaxations of densest k subgraph"
    - "santa claus schedules jobs on unrelated machines"
    - "new constructive aspects of the lovasz local lemma"
    - "greedy facility location algorithms analyzed using dual fitting with factor revealing lp"

Connected through hyperedge HE-6 (induced by source paper "fast clustering with lower bounds no customer too far no shop too small"):
  with members:
    - "net and prune a linear time algorithm for euclidean distance problems"
    - "minimum weight triangulation is np hard"
    - "fast construction of nets in low dimensional metrics and their applications"

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)