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: "bravo biased locking for reader writer locks"
  Abstract: Designers of modern reader-writer locks confront a difficult trade-off related to reader scalability. Locks that have a compact memory representation for active readers will typically suffer under high intensity read-dominated workloads when the "reader indicator"' state is updated frequently by a diverse set of threads, causing cache invalidation and coherence traffic. Other designs, such as cohort reader-writer locks, use distributed reader indicators, one per NUMA node. This improves reader-reader scalability, but also increases the size of each lock instance. #R##N#We propose a simple transformation BRAVO, that augments any existing reader-writer lock, adding just two integer fields to the lock instance. Readers make their presence known to writers by hashing their thread's identity with the lock address, forming an index into a visible readers table. Readers attempt to install the lock address into that element in the table, making their existence known to potential writers. All locks and threads in an address space can share the visible readers table. Updates by readers tend to be diffused over the table, resulting in a NUMA-friendly design. Crucially, readers of the same lock tend to write to different locations in the array, reducing coherence traffic. #R##N#Specifically, BRAVO allows a simple compact lock to be augmented so as to provide scalable concurrent reading but with only a modest increase in footprint.

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.OS(Operating Systems)