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: "smart contracts for the internet of things opportunities and challenges"
  Abstract: With the Internet of Things (IoT), Things are expected to live in different "domains" and "contexts" during their lifetime. Information generated by and associated with Things should be manageable by multiple, diverse stakeholders accordingly. Moreover, the scope of the information related to Things can range from private and confidential to public and auditable. Identification, security, and interoperability in this vivid environment are expected to be challenging. In this paper we discuss how smart contracts and blockchain technologies create the potential for a viable solution. To this end, we present smart contract-based solutions that improve security and information management, we identify new opportunities and challenges, and we provide security recommendations and guidelines.

Connected through hyperedge HE-1 (induced by source paper "secure iot access at scale using blockchains and smart contracts"):
  with members:
    - "smart contracts for machine to machine communication possibilities and limitations"
    - "smart contract based access control for the internet of things"

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.CY(Computers and Society)