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: "a survey on ethereum systems security vulnerabilities attacks and defenses"
  Abstract: The blockchain technology is believed by many to be a game changer in many application domains, especially financial applications. While the first generation of blockchain technology (i.e., Blockchain 1.0) is almost exclusively used for cryptocurrency purposes, the second generation (i.e., Blockchain 2.0), as represented by Ethereum, is an open and decentralized platform enabling a new paradigm of computing --- Decentralized Applications (DApps) running on top of blockchains. The rich applications and semantics of DApps inevitably introduce many security vulnerabilities, which have no counterparts in pure cryptocurrency systems like Bitcoin. Since Ethereum is a new, yet complex, system, it is imperative to have a systematic and comprehensive understanding on its security from a holistic perspective, which is unavailable. To the best of our knowledge, the present survey, which can also be used as a tutorial, fills this void. In particular, we systematize three aspects of Ethereum systems security: vulnerabilities, attacks, and defenses. We draw insights into, among other things, vulnerability root causes, attack consequences, and defense capabilities, which shed light on future research directions.

Connected through hyperedge HE-1 (induced by source paper "smart contract development from the perspective of developers topics and issues discussed on social media"):
  with members:
    - "when energy trading meets blockchain in electrical power system the state of the art"
    - "slither a static analysis framework for smart contracts"
    - "what are the actual flaws in important smart contracts and how can we find them"
    - "verisolid correct by design smart contracts for ethereum"
    - "manticore a user friendly symbolic execution framework for binaries and smart contracts"
    - "tool demonstration fsolidm for designing secure ethereum smart contracts"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "empirical vulnerability analysis of automated smart contracts security testing on blockchains"

Connected through hyperedge HE-2 (induced by source paper "vyper a security comparison with solidity based on common vulnerabilities"):
  with members:
    - "verisolid correct by design smart contracts for ethereum"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "empirical vulnerability analysis of automated smart contracts security testing on blockchains"
    - "towards safer smart contracts a survey of languages and verification methods"
    - "vandal a scalable security analysis framework for smart contracts"
    - "securify practical security analysis of smart contracts"
    - "designing secure ethereum smart contracts a finite state machine based approach"

Connected through hyperedge HE-3 (induced by source paper "smt friendly formalization of the solidity memory model"):
  with members:
    - "a minimal core calculus for solidity contracts"
    - "a semantic framework for the security analysis of ethereum smart contracts"
    - "formal specification and verification of smart contracts for azure blockchain"
    - "executable operational semantics of solidity"

Connected through hyperedge HE-4 (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"
    - "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"
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"

Connected through hyperedge HE-5 (induced by source paper "smart contract development in practice trends issues and discussions on stack overflow"):
  with members:
    - "when energy trading meets blockchain in electrical power system the state of the art"
    - "slither a static analysis framework for smart contracts"
    - "transax a blockchain based decentralized forward trading energy exchange for transactive microgrids"
    - "what are the actual flaws in important smart contracts and how can we find them"
    - "verisolid correct by design smart contracts for ethereum"
    - "manticore a user friendly symbolic execution framework for binaries and smart contracts"
    - "tool demonstration fsolidm for designing secure ethereum smart contracts"
    - "finding the greedy prodigal and suicidal contracts at scale"

Connected through hyperedge HE-6 (induced by source paper "empirical review of automated analysis tools on 47 587 ethereum smart contracts"):
  with members:
    - "the art of the scam demystifying honeypots in ethereum smart contracts"
    - "slither a static analysis framework for smart contracts"
    - "smart contract vulnerabilities does anyone care"
    - "domain specific code smells in smart contracts"
    - "manticore a user friendly symbolic execution framework for binaries and smart contracts"
    - "tool demonstration fsolidm for designing secure ethereum smart contracts"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "ethir a framework for high level analysis of ethereum bytecode"

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)