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: "on the complexity of submodular function minimisation on diamonds"
  Abstract: Let $(L; \sqcap, \sqcup)$ be a finite lattice and let $n$ be a positive integer. A function $f : L^n \to \mathbb{R}$ is said to be submodular if $f(\tup{a} \sqcap \tup{b}) + f(\tup{a} \sqcup \tup{b}) \leq f(\tup{a}) + f(\tup{b})$ for all $\tup{a}, \tup{b} \in L^n$. In this paper we study submodular functions when $L$ is a diamond. Given oracle access to $f$ we are interested in finding $\tup{x} \in L^n$ such that $f(\tup{x}) = \min_{\tup{y} \in L^n} f(\tup{y})$ as efficiently as possible. #R##N#We establish a min--max theorem, which states that the minimum of the submodular function is equal to the maximum of a certain function defined over a certain polyhedron; and a good characterisation of the minimisation problem, i.e., we show that given an oracle for computing a submodular $f : L^n \to \mathbb{Z}$ and an integer $m$ such that $\min_{\tup{x} \in L^n} f(\tup{x}) = m$, there is a proof of this fact which can be verified in time polynomial in $n$ and $\max_{\tup{t} \in L^n} \log |f(\tup{t})|$; and a pseudo-polynomial time algorithm for the minimisation problem, i.e., given an oracle for computing a submodular $f : L^n \to \mathbb{Z}$ one can find $\min_{\tup{t} \in L^n} f(\tup{t})$ in time bounded by a polynomial in $n$ and $\max_{\tup{t} \in L^n} |f(\tup{t})|$.

Connected through hyperedge HE-1 (induced by source paper "combinatorial optimization algorithms via polymorphisms"):
  with members:
    - "analysis of boolean functions"
    - "an algebraic theory of complexity for discrete optimization"
    - "rounding sum of squares relaxations"
    - "absorbing subalgebras cyclic terms and the constraint satisfaction problem"

Connected through hyperedge HE-2 (induced by source paper "towards minimizing k submodular functions"):
  with members:
    - "the complexity of conservative valued csps"
    - "the power of linear programming for valued csps"
    - "extensions of the minimum cost homomorphism problem"
    - "min csp on four elements moving beyond submodularity"
    - "submodularity on a tree unifying l natural convex and bisubmodular functions"
    - "the approximability of max csp with fixed value constraints"

Connected through hyperedge HE-3 (induced by source paper "oracle tractability of skew bisubmodular functions"):
  with members:
    - "the power of linear programming for valued csps"

Connected through hyperedge HE-4 (induced by source paper "the power of linear programming for valued csps"):
  with members:
    - "an algebraic theory of complexity for discrete optimization"
    - "the complexity of conservative valued csps"
    - "towards minimizing k submodular functions"
    - "min csp on four elements moving beyond submodularity"
    - "hard constraint satisfaction problems have hard gaps at location 1"
    - "the approximability of max csp with fixed value constraints"
    - "arc consistency for soft constraints"

Connected through hyperedge HE-5 (induced by source paper "submodularity on a tree unifying l natural convex and bisubmodular functions"):
  with members:
    - "min csp on four elements moving beyond submodularity"
    - "generalising tractable vcsps defined by symmetric tournament pair multimorphisms"
    - "a dichotomy theorem for conservative general valued csps"
    - "the complexity of conservative finite valued csps"

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)