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: "priority mechanism of bitcoin and its effect on transaction confirmation process"
  Abstract: In Bitcoin system, transactions are prioritized according to attributes such as the remittance amount and transaction fees, and transactions with low priority are likely to wait for confirmation. Because the demand of micro payment in Bitcoin is expected to increase due to low remittance cost, it is important to quantitatively investigate how the priority mechanism of Bitcoin affects the transaction-confirmation time. In this paper, we analyze the transaction-confirmation time by queueing theory. We model the transaction priority mechanism of Bitcoin as a priority queueing system with batch service, deriving the mean transaction-confirmation time. Numerical examples show how the demand of transactions of low remittance amount affects the transaction-confirmation time. We also consider the effect of the maximum block size on the transaction-confirmation time.

Connected through hyperedge HE-1 (induced by source paper "bitcoinf achieving fairness for bitcoin in transaction fee only model"):
  with members:
    - "predicting the confirmation time of bitcoin transactions"

Connected through hyperedge HE-2 (induced by source paper "markov processes in blockchain systems"):
  with members:
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "profitable double spending attacks"
    - "performance analysis of the raft consensus algorithm for private blockchains"
    - "a probabilistic model of the bitcoin blockchain"
    - "block arrivals in the bitcoin blockchain"
    - "blockchains consensus protocols in the wild"
    - "blockchain based smart contracts a systematic mapping study"
    - "an empirical analysis of smart contracts platforms applications and design patterns"

Connected through hyperedge HE-3 (induced by source paper "a delay tolerant payment scheme based on the ethereum blockchain"):
  with members:
    - "leader randomization signature free byzantine consensus for consortium blockchains"
    - "localcoin an ad hoc payment scheme for areas with high connectivity"
    - "the balance attack against proof of work blockchains the r3 testbed as an example"

Connected through hyperedge HE-4 (induced by source paper "predicting the confirmation time of bitcoin transactions"):
  with members:
    - "block arrivals in the bitcoin blockchain"

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.CR(Cryptography and Security)