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: "unsupervised common question generation from multiple documents using reinforced contrastive coordinator"
  Abstract: Web search engines today return a ranked list of document links in response to a user's query. However, when a user query is vague, the resultant documents span multiple subtopics. In such a scenario, it would be helpful if the search engine provided clarification options to the user's initial query in a way that each clarification option is closely related to the documents in one subtopic and is far away from the documents in all other subtopics. Motivated by this scenario, we address the task of contrastive common question generation where given a "positive" set of documents and a "negative" set of documents, we generate a question that is closely related to the "positive" set and is far away from the "negative" set. We propose Multi-Source Coordinated Question Generator (MSCQG), a novel coordinator model trained using reinforcement learning to optimize a reward based on document-question ranker score. We also develop an effective auxiliary objective, named Set-induced Contrastive Regularization (SCR) that draws the coordinator's generation behavior more closely toward "positive" documents and away from "negative" documents. We show that our model significantly outperforms strong retrieval baselines as well as a baseline model developed for a similar task, as measured by various metrics.

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.CL(Computation and Language)