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: "providing privacy safety and security in iot based transactive energy systems using distributed ledgers"
  Abstract: Power grids are undergoing major changes due to rapid growth in renewable energy resources and improvements in battery technology. While these changes enhance sustainability and efficiency, they also create significant management challenges as the complexity of power systems increases. To tackle these challenges, decentralized Internet-of-Things (IoT) solutions are emerging, which arrange local communities into transactive microgrids. Within a transactive microgrid, "prosumers" (i.e., consumers with energy generation and storage capabilities) can trade energy with each other, thereby smoothing the load on the main grid using local supply. It is hard, however, to provide security, safety, and privacy in a decentralized and transactive energy system. On the one hand, prosumers' personal information must be protected from their trade partners and the system operator. On the other hand, the system must be protected from careless or malicious trading, which could destabilize the entire grid. This paper describes Privacy-preserving Energy Transactions (PETra), which is a secure and safe solution for transactive microgrids that enables consumers to trade energy without sacrificing their privacy. PETra builds on distributed ledgers, such as blockchains, and provides anonymity for communication, bidding, and trading.

Connected through hyperedge HE-1 (induced by source paper "blockchain for the internet of things present and future"):
  with members:
    - "machine learning for wireless communications in the internet of things a comprehensive survey"
    - "block4forensic an integrated lightweight blockchain framework for forensics applications of connected vehicles"
    - "securing the internet of things in the age of machine learning and software defined networking"
    - "smart contract based access control for the internet of things"
    - "quality of information in mobile crowdsensing survey and research challenges"
    - "lsb a lightweight scalable blockchain for iot security and privacy"
    - "learning to detect and mitigate cross layer attacks in wireless networks framework and applications"
    - "blockchain a distributed solution to automotive security and privacy"

Connected through hyperedge HE-2 (induced by source paper "safe and private forward trading platform for transactive microgrids"):
  with members:
    - "transax a blockchain based decentralized forward trading energy exchange for transactive microgrids"
    - "decentralized p2p energy trading under network constraints in a low voltage network"
    - "solidworx a resilient and trustworthy transactive platform for smart and connected communities"
    - "hijacking bitcoin routing attacks on cryptocurrencies"
    - "bitcoin over tor isn t a good idea"
    - "increasing smart meter privacy through energy harvesting and storage devices"

Connected through hyperedge HE-3 (induced by source paper "privacy preserving p2p energy market on the blockchain"):
  with members:
    - "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
    - "encointer an ecological egalitarian and private cryptocurrency and self sovereign identity system"
    - "teechan payment channels using trusted execution environments"

Connected through hyperedge HE-4 (induced by source paper "cyber physical simulation platform for security assessment of transactive energy systems"):
  with members:
    - "verisolid correct by design smart contracts for ethereum"
    - "solidworx a resilient and trustworthy transactive platform for smart and connected communities"

Connected through hyperedge HE-5 (induced by source paper "transax a blockchain based decentralized forward trading energy exchange for transactive microgrids"):
  with members:
    - "solidworx a resilient and trustworthy transactive platform for smart and connected communities"
    - "increasing smart meter privacy through energy harvesting and storage devices"

Connected through hyperedge HE-6 (induced by source paper "blockchain for cities a systematic literature review"):
  with members:
    - "eductx a blockchain based higher education credit platform"
    - "blackchain scalability for resource constrained accountable vehicle to x communication"
    - "distributed protocols at the rescue for trustworthy online voting"
    - "deanonymisation of clients in bitcoin p2p network"

Connected through hyperedge HE-7 (induced by source paper "solidworx a resilient and trustworthy transactive platform for smart and connected communities"):
  with members:
    - "designing secure ethereum smart contracts a finite state machine based approach"
    - "on the design of communication and transaction anonymity in blockchain based transactive microgrids"

Connected through hyperedge HE-8 (induced by source paper "spb a secure private blockchain based solution for energy trading"):
  with members:
    - "atomic cross chain swaps"
    - "lsb a lightweight scalable blockchain for iot security and privacy"

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)