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: "do starting and ending effects in fixed price group buying differ"
  Abstract: With the growing popularity of group-buying websites, a plethora of group-buying options is available to consumers. Given this range of choices, information diffusion in group-buying can greatly influence consumers' purchase decisions. Our study uses large-scale datasets from the top two group-buying websites in China, to explore the diffusion process and examine mass media communication (MMC) and interpersonal communication (IPC) during different periods of the buying process. The analysis results indicate that MMC and IPC at the start of the process can positively affect the sales, while it leads to fewer sales during the ending period in fixed-price group-buying, which contradicts the results of previous studies. To the best of our knowledge, this is the first study to explore information diffusion in group- buying. This study provides a number of theoretical insights into group-buying from a new perspective, as well as practical management implications.

Connected through hyperedge HE-1 (induced by source paper "the warm start bias of yelp ratings"):
  with members:
    - "daily deals prediction social diffusion and reputational ramifications"

Connected through hyperedge HE-2 (induced by source paper "collective attention and the dynamics of group deals"):
  with members:
    - "the role of social networks in online shopping information passing price of trust and consumer choice"
    - "trends in social media persistence and decay"
    - "using a model of social dynamics to predict popularity of news"
    - "predicting the popularity of online content"
    - "analysis of social voting patterns on digg"
    - "novelty and collective attention"

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.SI(Social and Information Networks)