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: "critical independent sets of a graph"
  Abstract: Let $G$ be a simple graph with vertex set $V\left( G\right) $. A set $S\subseteq V\left( G\right) $ is independent if no two vertices from $S$ are adjacent, and by $\mathrm{Ind}(G)$ we mean the family of all independent sets of $G$. #R##N#The number $d\left( X\right) =$ $\left\vert X\right\vert -\left\vert N(X)\right\vert $ is the difference of $X\subseteq V\left( G\right) $, and a set $A\in\mathrm{Ind}(G)$ is critical if $d(A)=\max \{d\left( I\right) :I\in\mathrm{Ind}(G)\}$ (Zhang, 1990). #R##N#Let us recall the following definitions: #R##N#$\mathrm{core}\left( G\right) $ = $\bigcap$ {S : S is a maximum independent set}. #R##N#$\mathrm{corona}\left( G\right)$ = $\bigcup$ {S :S is a maximum independent set}. #R##N#$\mathrm{\ker}(G)$ = $\bigcap$ {S : S is a critical independent set}. #R##N#$\mathrm{diadem}(G)$ = $\bigcup$ {S : S is a critical independent set}. #R##N#In this paper we present various structural properties of $\mathrm{\ker}(G)$, in relation with $\mathrm{core}\left( G\right) $, $\mathrm{corona}\left( G\right) $, and $\mathrm{diadem}(G)$.

Connected through hyperedge HE-1 (induced by source paper "on konig egervary collections of maximum critical independent sets"):
  with members:
    - "critical and maximum independent sets of a graph"
    - "monotonic properties of collections of maximum independent sets of a graph"
    - "a set and collection lemma"
    - "vertices belonging to all critical independent sets of a graph"

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)