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: "serializable snapshot isolation in postgresql"
  Abstract: This paper describes our experience implementing PostgreSQL's new serializable isolation level. It is based on the recently-developed Serializable Snapshot Isolation (SSI) technique. This is the first implementation of SSI in a production database release as well as the first in a database that did not previously have a lock-based serializable isolation level. We reflect on our experience and describe how we overcame some of the resulting challenges, including the implementation of a new lock manager, a technique for ensuring memory usage is bounded, and integration with other PostgreSQL features. We also introduce an extension to SSI that improves performance for read-only transactions. We evaluate PostgreSQL's serializable isolation level using several benchmarks and show that it achieves performance only slightly below that of snapshot isolation, and significantly outperforms the traditional two-phase locking approach on read-intensive workloads.

Connected through hyperedge HE-1 (induced by source paper "analysis of indexing structures for immutable data full version"):
  with members:
    - "a critique of ansi sql isolation levels"

Connected through hyperedge HE-2 (induced by source paper "lockless transaction isolation in hyperledger fabric"):
  with members:
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "performance benchmarking and optimizing hyperledger fabric blockchain platform"
    - "blockchains consensus protocols in the wild"
    - "adding concurrency to smart contracts"
    - "a critique of ansi sql isolation levels"

Connected through hyperedge HE-3 (induced by source paper "blockchain meets database design and implementation of a blockchain relational database"):
  with members:
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "xft practical fault tolerance beyond crashes"
    - "middleware based database replication the gaps between theory and practice"
    - "a critique of ansi sql isolation levels"
    - "consensus on transaction commit"

Connected through hyperedge HE-4 (induced by source paper "nwr rethinking thomas write rule for omittable write operations"):
  with members:
    - "efficiently making almost any concurrency control mechanism serializable"
    - "high performance concurrency control mechanisms for main memory databases"
    - "a critique of ansi sql isolation levels"

Connected through hyperedge HE-5 (induced by source paper "detecting incorrect behavior of cloud databases as an outsider"):
  with members:
    - "automated detection of serializability violations under weak consistency"
    - "on the quest for an acyclic graph"
    - "sat modulo monotonic theories"

Connected through hyperedge HE-6 (induced by source paper "stretching the capacity of hardware transactional memory in ibm power architectures"):
  with members:
    - "the end of a myth distributed transactions can scale"
    - "a critique of ansi sql isolation levels"

Connected through hyperedge HE-7 (induced by source paper "efficiently making almost any concurrency control mechanism serializable"):
  with members:
    - "rethinking serializable multiversion concurrency control"
    - "high performance concurrency control mechanisms for main memory databases"
    - "a critique of ansi sql isolation levels"

Connected through hyperedge HE-8 (induced by source paper "posterior snapshot isolation"):
  with members:
    - "rethinking serializable multiversion concurrency control"
    - "a critique of ansi sql isolation levels"

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.DB(Databases)