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: "minimum cost homomorphisms to semicomplete multipartite digraphs"
  Abstract: For digraphs $D$ and $H$, a mapping $f: V(D)\dom V(H)$ is a {\em homomorphism of $D$ to $H$} if $uv\in A(D)$ implies $f(u)f(v)\in A(H).$ For a fixed directed or undirected graph $H$ and an input graph $D$, the problem of verifying whether there exists a homomorphism of $D$ to $H$ has been studied in a large number of papers. We study an optimization version of this decision problem. Our optimization problem is motivated by a real-world problem in defence logistics and was introduced very recently by the authors and M. Tso. #R##N#Suppose we are given a pair of digraphs $D,H$ and a positive integral cost $c_i(u)$ for each $u\in V(D)$ and $i\in V(H)$. The cost of a homomorphism $f$ of $D$ to $H$ is $\sum_{u\in V(D)}c_{f(u)}(u)$. Let $H$ be a fixed digraph. The minimum cost homomorphism problem for $H$, MinHOMP($H$), is stated as follows: For input digraph $D$ and costs $c_i(u)$ for each $u\in V(D)$ and $i\in V(H)$, verify whether there is a homomorphism of $D$ to $H$ and, if it does exist, find such a homomorphism of minimum cost. In our previous paper we obtained a dichotomy classification of the time complexity of \MiP for $H$ being a semicomplete digraph. In this paper we extend the classification to semicomplete $k$-partite digraphs, $k\ge 3$, and obtain such a classification for bipartite tournaments.

Connected through hyperedge HE-1 (induced by source paper "minimum cost homomorphisms to locally semicomplete and quasi transitive digraphs"):
  with members:
    - "a maximal tractable class of soft constraints"
    - "minimum cost homomorphisms to reflexive digraphs"
    - "minimum cost and list homomorphisms to semicomplete digraphs"

Connected through hyperedge HE-2 (induced by source paper "minimum cost homomorphisms to reflexive digraphs"):
  with members:
    - "a maximal tractable class of soft constraints"
    - "on the complexity of the minimum cost homomorphism problem for reflexive multipartite tournaments"
    - "minimum cost and list homomorphisms to semicomplete digraphs"

Connected through hyperedge HE-3 (induced by source paper "on the complexity of the minimum cost homomorphism problem for reflexive multipartite tournaments"):
  with members:
    - "minimum cost homomorphisms to proper interval graphs and bigraphs"
    - "minimum cost and list homomorphisms to semicomplete digraphs"

Connected through hyperedge HE-4 (induced by source paper "complexity of the minimum cost homomorphism problem for semicomplete digraphs with possible loops"):
  with members:
    - "minimum cost and list homomorphisms to semicomplete digraphs"

Connected through hyperedge HE-5 (induced by source paper "minimum cost homomorphisms to proper interval graphs and bigraphs"):
  with members:
    - "a maximal tractable class of soft constraints"
    - "minimum cost and list homomorphisms to semicomplete digraphs"

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)