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: "online detection of effectively callback free objects with applications to smart contracts"
  Abstract: Callbacks are essential in many programming environments, but drastically complicate program understanding and reasoning because they allow to mutate object's local states by external objects in unexpected fashions, thus breaking modularity. The famous DAO bug in the cryptocurrency framework Ethereum, employed callbacks to steal $150M. We define the notion of Effectively Callback Free (ECF) objects in order to allow callbacks without preventing modular reasoning. #R##N#An object is ECF in a given execution trace if there exists an equivalent execution trace without callbacks to this object. An object is ECF if it is ECF in every possible execution trace. We study the decidability of dynamically checking ECF in a given execution trace and statically checking if an object is ECF. We also show that dynamically checking ECF in Ethereum is feasible and can be done online. By running the history of all execution traces in Ethereum, we were able to verify that virtually all existing contracts, excluding the DAO or contracts with similar known vulnerabilities, are ECF. Finally, we show that ECF, whether it is verified dynamically or statically, enables modular reasoning about objects with encapsulated state.

Connected through hyperedge HE-1 (induced by source paper "smacs smart contract access control service"):
  with members:
    - "sereum protecting existing smart contracts against re entrancy attacks"
    - "vandal a scalable security analysis framework for smart contracts"
    - "securify practical security analysis of smart contracts"

Connected through hyperedge HE-2 (induced by source paper "a survey on ethereum systems security vulnerabilities attacks and defenses"):
  with members:
    - "security and privacy on blockchain"
    - "exploring the attack surface of blockchain a systematic overview"
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "metrics towards measuring cyber agility"
    - "selfish mining in ethereum"
    - "a survey of distributed consensus protocols for blockchain networks"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "ethir a framework for high level analysis of ethereum bytecode"

Connected through hyperedge HE-3 (induced by source paper "targeted greybox fuzzing with static lookahead analysis"):
  with members:
    - "v fuzz vulnerability oriented evolutionary fuzzing"
    - "harvey a greybox fuzzer for smart contracts"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "quantitative analysis of smart contracts"
    - "fairfuzz a targeted mutation strategy for increasing greybox fuzz testing coverage"
    - "evaluating fuzz testing"
    - "contractfuzzer fuzzing smart contracts for vulnerability detection"
    - "learning inputs in greybox fuzzing"

Connected through hyperedge HE-4 (induced by source paper "safevm a safety verifier for ethereum smart contracts"):
  with members:
    - "exploiting the laws of order in smart contracts"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "ethir a framework for high level analysis of ethereum bytecode"
    - "gastap a gas analyzer for smart contracts"
    - "a semantic framework for the security analysis of ethereum smart contracts"
    - "vandal a scalable security analysis framework for smart contracts"
    - "securify practical security analysis of smart contracts"
    - "under optimized smart contracts devour your money"

Connected through hyperedge HE-5 (induced by source paper "verismart a highly precise safety verifier for ethereum smart contracts"):
  with members:
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "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"
    - "formal specification and verification of smart contracts for azure blockchain"
    - "vandal a scalable security analysis framework for smart contracts"
    - "securify practical security analysis of smart contracts"
    - "under optimized smart contracts devour your money"

Connected through hyperedge HE-6 (induced by source paper "harvey a greybox fuzzer for smart contracts"):
  with members:
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "quantitative analysis of smart contracts"
    - "evaluating fuzz testing"
    - "contractfuzzer fuzzing smart contracts for vulnerability detection"
    - "vandal a scalable security analysis framework for smart contracts"
    - "angora efficient fuzzing by principled search"
    - "securify practical security analysis of smart contracts"
    - "a concurrent perspective on smart contracts"

Connected through hyperedge HE-7 (induced by source paper "smart contract repair"):
  with members:
    - "slither a static analysis framework for smart contracts"
    - "mutation testing for ethereum smart contract"
    - "contractfuzzer fuzzing smart contracts for vulnerability detection"
    - "a semantic framework for the security analysis of ethereum smart contracts"
    - "automatic software repair a bibliography"
    - "on the specification and verification of atomic swap smart contracts"
    - "securify practical security analysis of smart contracts"
    - "nopol automatic repair of conditional statement bugs in java programs"

Connected through hyperedge HE-8 (induced by source paper "basis path coverage criteria for smart contract application testing"):
  with members:
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "contractfuzzer fuzzing smart contracts for vulnerability detection"
    - "a semantic framework for the security analysis of ethereum smart contracts"
    - "vandal a scalable security analysis framework for smart contracts"
    - "blockchains consensus protocols in the wild"
    - "under optimized smart contracts devour your money"
    - "an empirical analysis of smart contracts platforms applications and design patterns"
    - "smart contract templates foundations design landscape and research directions"

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.PL(Programming Languages)