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: "finding the submodularity hidden in symmetric difference"
  Abstract: A fundamental property of convex functions in continuous space is that the convexity is preserved under affine transformations. A set function $f$ on a finite set $V$ is {\em submodular} if $f(X) + f(Y) \geq f(X \cup Y) - f(X \cap Y)$ for any pair $X, Y \subseteq V$. The {\em symmetric difference transformation} ({\em SD-transformation}) of $f$ by a {\em canonical set} $S \subseteq V$ is a set function $g$ given by $g(X) = f(X \vartriangle S)$ for $X \subseteq V$, where $X \vartriangle S = (X \setminus S) \cup (S \setminus X)$ is the {\it symmetric difference} between $X$ and $S$. Despite that submodular functions and SD-transformations are regarded as counterparts of convex functions and affine transformations in finite discrete space, not all SD-transformations do not preserve the submodularity. Starting with a characterization of SD-stransformations that preserve the submodularity, this paper investigates the problem of discovering a canonical set $S$, given the SD-transformation $g$ of a submodular function $f$ by $S$, provided that $g(X)$ is given by an oracle. A submodular function $f$ on $V$ is said to be {\it strict} if $f(X) + f(Y) > f(X \cup Y) - f(X \cap Y)$ holds whenever both $X \setminus Y$ and $Y \setminus X$ are nonempty. We show that the problem is solvable by using ${\rm O}(|V|)$ oracle calls when $f$ is strictly submodular, although it requires exponentially many oracle calls in general.

Connected through hyperedge HE-1 (induced by source paper "any finite distributive lattice is isomorphic to the minimizer set of an rm m natural concave set function"):
  with members:
    - "bis hardness for 2 spin systems on bipartite bounded degree graphs in the tree non uniqueness region"
    - "a faster cutting plane method and its implications for combinatorial and convex optimization"

Connected through hyperedge HE-2 (induced by source paper "supermodular locality sensitive hashes"):
  with members:
    - "testing submodularity and other properties of valuation functions"
    - "slack and margin rescaling as convex extensions of supermodular functions"
    - "submodular hamming metrics"
    - "learning with submodular functions a convex optimization perspective"
    - "is submodularity testable"

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.DM(Discrete Mathematics)