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: "executable formal semantics for the posix shell"
  Abstract: The POSIX shell is a widely deployed, powerful tool for managing computer systems. The shell is the expert's control panel, a necessary tool for configuring, compiling, installing, maintaining, and deploying systems. Even though it is powerful, critical infrastructure, the POSIX shell is maligned and misunderstood. Its power and its subtlety are a dangerous combination. #R##N#We define a formal, mechanized, executable small-step semantics for the POSIX shell, which we call Smoosh. We compared Smoosh against seven other shells that aim for some measure of POSIX compliance (bash, dash, zsh, OSH, mksh, ksh93, and yash). Using three test suites---the POSIX test suite, the Modernish test suite and shell diagnosis, and a test suite of our own device---we found Smoosh's semantics to be the most conformant to the POSIX standard. Modernish judges Smoosh to have the fewest bugs (just one, from using dash's parser) and no quirks. To show that our semantics is useful beyond yielding a conformant, executable shell, we also implemented a symbolic stepper to illuminate the subtle behavior of the shell. #R##N#Smoosh will serve as a foundation for formal study of the POSIX shell, supporting research on and development of new shells, new tooling for shells, and new shell designs.

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)