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: "when internet of things meets blockchain challenges in distributed consensus"
  Abstract: Blockchain has been regarded as a promising technology for Internet of Things (IoT), since it provides significant solutions for decentralized network which can address trust and security concerns, high maintenance cost problem, etc. The decentralization provided by blockchain can be largely attributed to the use of consensus mechanism, which enables peer-to-peer trading in a distributed manner without the involvement of any third party. This article starts from introducing the basic concept of blockchain and illustrating why consensus mechanism plays an indispensable role in a blockchain enabled IoT system. Then, we discuss the main ideas of two famous consensus mechanisms including Proof of Work (PoW) and Proof of Stake (PoS), and list their limitations in IoT. Next, two mainstream Direct Acyclic Graph (DAG) based consensus mechanisms, i.e., the Tangle and Hashgraph, are reviewed to show why DAG consensus is more suitable for IoT system than PoW and PoS. Potential issues and challenges of DAG based consensus mechanism to be addressed in the future are discussed in the last.

Connected through hyperedge HE-1 (induced by source paper "joint power splitting and relay selection in energy harvesting communications for iot networks"):
  with members:
    - "cooperative ambient backscatter communications for green internet of things"
    - "optimization of a power splitting protocol for two way multiple energy harvesting relay system"
    - "incentive mechanism design for wireless energy harvesting based internet of things"
    - "practical non linear energy harvesting model and resource allocation for swipt systems"
    - "optimal cooperative power allocation for energy harvesting enabled relay networks"
    - "outage probability of energy harvesting relay aided cooperative networks over rayleigh fading channel"
    - "power allocation strategies in energy harvesting wireless cooperative networks"
    - "exploiting network cooperation in green wireless communication"

Connected through hyperedge HE-2 (induced by source paper "computation offloading in the untrusted mec aided mobile blockchain iot system"):
  with members:
    - "blockchain for internet of things a survey"
    - "delay and communication tradeoffs for blockchain systems with lightweight iot clients"
    - "auction mechanisms in cloud fog computing resource allocation for public blockchain networks"
    - "cloud fog computing resource management and pricing for blockchain networks"
    - "analysis of the communication traffic for blockchain synchronization of iot devices"
    - "when mobile blockchain meets edge computing"
    - "a survey on mobile edge computing the communication perspective"
    - "social welfare maximization auction in edge computing resource allocation for mobile blockchain"

Connected through hyperedge HE-3 (induced by source paper "direct acyclic graph based blockchain for internet of things performance and security analysis"):
  with members:
    - "blockchain a distributed solution to automotive security and privacy"
    - "analysis of hashrate based double spending"

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.DC(Distributed, Parallel, and Cluster Computing)