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: "proof of work without all the work"
  Abstract: Proof-of-work (PoW) is a popular algorithmic tool used to enhance network security by imposing a computational cost on participating devices. Unfortunately, traditional PoW schemes require that correct devices work perpetually in order to remain vigilant against possible malicious behavior. In other words, computational costs are unbounded regardless of whether the network is under attack. This shortcoming is highlighted by recent studies showing that PoW is highly inefficient with respect to operating cost and ecological footprint. #R##N#We address this issue by designing a general PoW scheme for securing open distributed systems, whereby the cost to devices grows slowly as a function of the cost incurred by an attacker. Consequently, if the network is attacked, our scheme guarantees security, with algorithmic costs that are commensurate with the cost of the attacker. Conversely, in the absence of attack, algorithmic costs are small. #R##N#Our results hold in a dynamic system where participants join and depart over time. We demonstrate how our PoW scheme can be leveraged to address important security problems in distributed computing including: Sybil attacks, Byzantine consensus, and Committee election.

Connected through hyperedge HE-1 (induced by source paper "resource competitive sybil defenses"):
  with members:
    - "secure one way interactive communication"
    - "torbricks blocking resistant tor bridge distribution"
    - "interactive communication with unknown noise rate"
    - "bitcoin ng a scalable blockchain protocol"
    - "the mason test a defense against sybil attacks in wireless networks without trusted authorities"
    - "self healing computation"
    - "the sybil attacks and defenses a survey"
    - "quorums quicken queries efficient asynchronous secure multiparty computation"

Connected through hyperedge HE-2 (induced by source paper "proof of execution reaching consensus through fault tolerant speculation"):
  with members:
    - "blockchain meets database design and implementation of a blockchain relational database"
    - "vchain enabling verifiable boolean range queries over blockchain databases"
    - "towards scaling blockchain systems via sharding"
    - "scaling nakamoto consensus to thousands of transactions per second"
    - "the gap game"
    - "blockbench a framework for analyzing private blockchains"
    - "revisiting fast practical byzantine fault tolerance"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"

Connected through hyperedge HE-3 (induced by source paper "on the convergence of blockchain and internet of things iot technologies"):
  with members:
    - "blockchain technologies for the internet of things research issues and challenges"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "analysis of the communication traffic for blockchain synchronization of iot devices"
    - "blockchain based smart contracts a systematic mapping study"
    - "blockchain in internet of things challenges and solutions"
    - "bitcoin ng a scalable blockchain protocol"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-4 (induced by source paper "flow separating consensus and compute"):
  with members:
    - "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
    - "scalable byzantine consensus via hardware assisted secret sharing"
    - "proteus a scalable bft consesus protocol for blockchains"
    - "hotstuff bft consensus in the lens of blockchain"
    - "sbft a scalable decentralized trust infrastructure for blockchains"
    - "betting on blockchain consensus with fantomette"
    - "consensus in the age of blockchains"

Connected through hyperedge HE-5 (induced by source paper "proof of work without all the work computationally efficient attack resistant systems"):
  with members:
    - "secure one way interactive communication"
    - "torbricks blocking resistant tor bridge distribution"
    - "interactive communication with unknown noise rate"
    - "the mason test a defense against sybil attacks in wireless networks without trusted authorities"
    - "self healing computation"
    - "the sybil attacks and defenses a survey"
    - "storage and search in dynamic peer to peer networks"
    - "making evildoers pay resource competitive broadcast in sensor networks"

Connected through hyperedge HE-6 (induced by source paper "tiny groups tackle byzantine adversaries"):
  with members:
    - "algorand the efficient and democratic ledger"
    - "self healing computation"
    - "storage and search in dynamic peer to peer networks"
    - "sybilcontrol practical sybil defense with computational puzzles"
    - "breaking the o n 2 bit barrier scalable byzantine agreement with an adaptive adversary"

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)