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 "average stretch factor how low does it go"):
  Abstract: In a geometric graph, $G$, the \emph{stretch factor} between two vertices, $u$ and $w$, is the ratio between the Euclidean length of the shortest path from $u$ to $w$ in $G$ and the Euclidean distance between $u$ and $w$. The \emph{average stretch factor} of $G$ is the average stretch factor taken over all pairs of vertices in $G$. We show that, for any constant dimension, $d$, and any set, $V$, of $n$ points in $\mathbb{R}^d$, there exists a geometric graph with vertex set $V$, that has $O(n)$ edges, and that has average stretch factor $1+ o_n(1)$. More precisely, the average stretch factor of this graph is $1+O((\log n/n)^{1/(2d+1)})$. We complement this upper-bound with a lower bound: There exist $n$-point sets in $\mathbb{R}^2$ for which any graph with $O(n)$ edges has average stretch factor $1+\Omega(1/\sqrt{n})$. Bounds of this type are not possible for the more commonly studied worst-case stretch factor. In particular, there exists point sets, $V$, such that any graph with worst-case stretch factor $1+o_n(1)$ has a superlinear number of edges.

Includes members:
  Member "robust geometric spanners":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "piecewise linear regressions for approximating distance metrics")
  Member "embedding metrics into ultrametrics and graphs into spanning trees with constant average distortion":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "covering metric spaces by few trees")

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.CG(Computational Geometry)