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: "typing copyless message passing"
  Abstract: We present a calculus that models a form of process interaction based on#N#copyless message passing, in the style of Singularity OS. The calculus is#N#equipped with a type system ensuring that well-typed processes are free from#N#memory faults, memory leaks, and communication errors. The type system is#N#essentially linear, but we show that linearity alone is inadequate, because it#N#leaves room for scenarios where well-typed processes leak significant amounts#N#of memory. We address these problems basing the type system upon an original#N#variant of session types.

Connected through hyperedge HE-1 (induced by source paper "core higher order session processes tractable equivalences and relative expressiveness"):
  with members:
    - "musings on encodings and expressiveness"
    - "contextual equivalence for higher order pi calculus revisited"
    - "comparing the expressive power of the synchronous and asynchronous pi calculi"

Connected through hyperedge HE-2 (induced by source paper "from lock freedom to progress using session types"):
  with members:
    - "essential convexity and complexity of semi algebraic constraints"
    - "session types intersection types union types"

Connected through hyperedge HE-3 (induced by source paper "shared contract obedient endpoints"):
  with members:
    - "permission based separation logic for message passing concurrency"
    - "a type checking algorithm for qualified session types"

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)