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: "blockchain based smart contracts a systematic mapping study"
  Abstract: An appealing feature of blockchain technology is smart contracts. A smart contract is executable code that runs on top of the blockchain to facilitate, execute and enforce an agreement between untrusted parties without the involvement of a trusted third party. In this paper, we conduct a systematic mapping study to collect all research that is relevant to smart contracts from a technical perspective. The aim of doing so is to identify current research topics and open challenges for future studies in smart contract research. We extract 24 papers from different scientific databases. The results show that about two thirds of the papers focus on identifying and tackling smart contract issues. Four key issues are identified, namely, codifying, security, privacy and performance issues. The rest of the papers focuses on smart contract applications or other smart contract related topics. Research gaps that need to be addressed in future studies are provided.

Connected through hyperedge HE-1 (induced by source paper "an overview on smart contracts challenges advances and platforms"):
  with members:
    - "the art of the scam demystifying honeypots in ethereum smart contracts"
    - "blockchain for internet of things a survey"
    - "evmfuzz differential fuzz testing of ethereum virtual machine"
    - "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"
    - "sabre protecting bitcoin against routing attacks"
    - "hunting the ethereum smart contract color inspired inspection of potential attacks"

Connected through hyperedge HE-2 (induced by source paper "checking smart contracts with structural code embedding"):
  with members:
    - "automating app review response generation"
    - "smartembed a tool for clone and bug detection in smart contracts through structural code embedding"
    - "sorting and transforming program repair ingredients via deep learning code similarities"
    - "a general path based representation for predicting program properties"
    - "a survey on the security of blockchain systems"
    - "under optimized smart contracts devour your money"
    - "an empirical analysis of smart contracts platforms applications and design patterns"
    - "dynamic neural program embedding for program repair"

Connected through hyperedge HE-3 (induced by source paper "security analysis methods on ethereum smart contract vulnerabilities a survey"):
  with members:
    - "easyflow keep ethereum away from overflow"
    - "a security case study for blockchain games"
    - "a hybrid formal verification system in coq for ensuring the reliability and security of ethereum based service smart contracts"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "ethir a framework for high level analysis of ethereum bytecode"
    - "formal process virtual machine for smart contracts verification"
    - "scilla a smart contract intermediate level language"
    - "empirical vulnerability analysis of automated smart contracts security testing on blockchains"

Connected through hyperedge HE-4 (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"
    - "an empirical analysis of smart contracts platforms applications and design patterns"
    - "bitcoin s security model revisited"

Connected through hyperedge HE-5 (induced by source paper "gasfuzz generating high gas consumption inputs to avoid out of gas vulnerability"):
  with members:
    - "evmfuzz differential fuzz testing of ethereum virtual machine"
    - "the ico phenomenon and its relationships with ethereum smart contract environment"
    - "gastap a gas analyzer for smart contracts"
    - "contractfuzzer fuzzing smart contracts for vulnerability detection"
    - "a semantic framework for the security analysis of ethereum smart contracts"
    - "enfuzz from ensemble learning to ensemble fuzzing"
    - "vandal a scalable security analysis framework for smart contracts"
    - "securify practical security analysis of smart contracts"

Connected through hyperedge HE-6 (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"
    - "proof of work without all the work"
    - "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-7 (induced by source paper "a survey on efficient parallelization of blockchain based smart contracts"):
  with members:
    - "blockclique scaling blockchains through transaction sharding in a multithreaded block graph"
    - "chainspace a sharded smart contracts platform"
    - "adding concurrency to smart contracts"
    - "centrally banked cryptocurrencies"

Connected through hyperedge HE-8 (induced by source paper "blockchain technologies for smart energy systems fundamentals challenges and solutions"):
  with members:
    - "peer to peer and community based markets a comprehensive review"
    - "a first look at identity management schemes on the blockchain"
    - "implicit consensus blockchain with unbounded throughput"
    - "untangling blockchain a data processing view of blockchain systems"

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)