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: "casper the friendly finality gadget"
  Abstract: We introduce Casper, a proof of stake-based finality system which overlays an existing proof of work blockchain. Casper is a partial consensus mechanism combining proof of stake algorithm research and Byzantine fault tolerant consensus theory. We introduce our system, prove some desirable features, and show defenses against long range revisions and catastrophic crashes. The Casper overlay provides almost any proof of work chain with additional protections against block reversions.

Connected through hyperedge HE-1 (induced by source paper "surface a practical blockchain consensus algorithm for real world networks"):
  with members:
    - "rationality is self defeating in permissionless systems"
    - "dfinity technology overview series consensus system"
    - "hotstuff bft consensus in the lens of blockchain"
    - "deconstructing the blockchain to approach physical limits"
    - "scaling nakamoto consensus to thousands of transactions per second"
    - "transaction propagation on permissionless blockchains incentive and routing mechanisms"
    - "implicit consensus blockchain with unbounded throughput"
    - "chainspace a sharded smart contracts platform"

Connected through hyperedge HE-2 (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"
    - "consensus in the age of blockchains"
    - "towards a concurrent and distributed route selection for payment channel networks"
    - "settling payments fast and private efficient decentralized routing for path based transactions"
    - "voute virtual overlays using tree embeddings"

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"
    - "consensus in the age of blockchains"
    - "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"
    - "consensus in the age of blockchains"
    - "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"
    - "consensus in the age of blockchains"
    - "cryptocurrencies without proof of work"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-6 (induced by source paper "pigpaxos devouring the communication bottlenecks in distributed consensus"):
  with members:
    - "cross chain deals and adversarial commerce"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "wpaxos wide area network flexible consensus"
    - "flexible paxos quorum intersection revisited"

Connected through hyperedge HE-7 (induced by source paper "blockchain based decentralized applications technology review and development guidelines"):
  with members:
    - "a scalable verification solution for blockchains"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "augur a decentralized open source platform for prediction markets"

Connected through hyperedge HE-8 (induced by source paper "combining ghost and casper"):
  with members:
    - "dfinity technology overview series consensus system"
    - "the latest gossip on bft consensus"
    - "hotstuff bft consensus in the lens of 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)