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: "consensus in the age of blockchains"
  Abstract: The blockchain initially gained traction in 2008 as the technology underlying bitcoin, but now has been employed in a diverse range of applications and created a global market worth over $150B as of 2017. What distinguishes blockchains from traditional distributed databases is the ability to operate in a decentralized setting without relying on a trusted third party. As such their core technical component is consensus: how to reach agreement among a group of nodes. This has been extensively studied already in the distributed systems community for closed systems, but its application to open blockchains has revitalized the field and led to a plethora of new designs. #R##N#The inherent complexity of consensus protocols and their rapid and dramatic evolution makes it hard to contextualize the design landscape. We address this challenge by conducting a systematic and comprehensive study of blockchain consensus protocols. After first discussing key themes in classical consensus protocols, we describe: first protocols based on proof-of-work (PoW), second proof-of-X (PoX) protocols that replace PoW with more energy-efficient alternatives, and third hybrid protocols that are compositions or variations of classical consensus protocols. We develop a framework to evaluate their performance, security and design properties, and use it to systematize key themes in the protocol categories described above. This evaluation leads us to identify research gaps and challenges for the community to consider in future research endeavours.

Connected through hyperedge HE-1 (induced by source paper "hushrelay a privacy preserving efficient and scalable routing algorithm for off chain payments"):
  with members:
    - "concurrency and privacy with payment channel networks"
    - "topological analysis of bitcoin s lightning network"
    - "ant routing algorithm for the lightning network"
    - "routing cryptocurrency with the spider network"
    - "towards a concurrent and distributed route selection for payment channel networks"
    - "casper the friendly finality gadget"
    - "settling payments fast and private efficient decentralized routing for path based transactions"
    - "voute virtual overlays using tree embeddings"

Connected through hyperedge HE-2 (induced by source paper "tenderbake classical bft style consensus for public blockchains"):
  with members:
    - "correctness analysis of ibft"
    - "introduction to the tezos blockchain"
    - "dissecting tendermint"
    - "dfinity technology overview series consensus system"
    - "the latest gossip on bft consensus"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "blockchains consensus protocols in the wild"
    - "leader randomization signature free byzantine consensus for consortium blockchains"

Connected through hyperedge HE-3 (induced by source paper "snappy fast on chain payments with practical collaterals"):
  with members:
    - "dfinity technology overview series consensus system"
    - "gosig scalable byzantine consensus on adversarial wide area network for blockchains"
    - "towards an economic analysis of routing in payment channel networks"
    - "sprites and state channels payment networks that go faster than lightning"
    - "casper the friendly finality gadget"
    - "strong federations an interoperable blockchain solution to centralized third party risks"

Connected through hyperedge HE-4 (induced by source paper "blockchain consensus algorithms a survey"):
  with members:
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "blockchains consensus protocols in the wild"
    - "casper the friendly finality gadget"
    - "cryptocurrencies without proof of work"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-5 (induced by source paper "blockchain consensuses algorithms a survey"):
  with members:
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "blockchains consensus protocols in the wild"
    - "casper the friendly finality gadget"
    - "cryptocurrencies without proof of work"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-6 (induced by source paper "modeling the impact of network connectivity on consensus security of proof of work blockchain"):
  with members:
    - "a survey of distributed consensus protocols for blockchain networks"
    - "decentralization in bitcoin and ethereum networks"
    - "optimal selfish mining strategies in bitcoin"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-7 (induced by source paper "the security reference architecture for blockchains towards a standardized model for studying vulnerabilities threats and defenses"):
  with members:
    - "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
    - "a survey on ethereum systems security vulnerabilities attacks and defenses"
    - "security and privacy on blockchain"
    - "deconstructing blockchains a comprehensive survey on consensus membership and structure"
    - "truffle tests for free replaying ethereum smart contracts for transparency"
    - "blockchain technologies for the internet of things research issues and challenges"
    - "exploring the attack surface of blockchain a systematic overview"
    - "strongchain transparent and collaborative proof of work consensus"

Connected through hyperedge HE-8 (induced by source paper "a survey on consensus mechanisms and mining strategy management in blockchain networks"):
  with members:
    - "decentralization in bitcoin and ethereum networks"
    - "information and communications technologies for sustainable development goals state of the art needs and perspectives"
    - "a scale out blockchain for value transfer with spontaneous sharding"
    - "a survey on security and privacy issues of bitcoin"
    - "on cyber risk management of blockchain networks a game theoretic approach"
    - "scaling nakamoto consensus to thousands of transactions per second"
    - "competitive data trading in wireless powered internet of things iot crowdsensing systems with blockchain"
    - "blockchained on device federated learning"

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)