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: "a graphical approach to progress for structured communication in web services"
  Abstract: We investigate a graphical representation of session invocation interdependency in order to prove progress for the pi-calculus with sessions under the usual session typing discipline. We show that those processes whose associated dependency graph is acyclic can be brought to reduce. We call such processes transparent processes. Additionally, we prove that for well-typed processes where services contain no free names, such acyclicity is preserved by the reduction semantics. #R##N#Our results encompass programs (processes containing neither free nor restricted session channels) and higher-order sessions (delegation). Furthermore, we give examples suggesting that transparent processes constitute a large enough class of processes with progress to have applications in modern session-based programming languages for web services.

Connected through hyperedge HE-1 (induced by source paper "comparing type systems for deadlock freedom"):
  with members:
    - "comparing deadlock free session typed processes"
    - "unlocking blocked communicating processes"
    - "recursive session types revisited"
    - "from lock freedom to progress using session types"

Connected through hyperedge HE-2 (induced by source paper "type checking liveness for collaborative processes with bounded and unbounded recursion"):
  with members:
    - "multiparty compatibility in communicating automata characterisation and synthesis of global session types"
    - "from lock freedom to progress using session types"
    - "explicit fairness in testing semantics"

Connected through hyperedge HE-3 (induced by source paper "linearly typed dyadic group sessions for building multiparty sessions"):
  with members:
    - "session types in a linearly typed multi threaded lambda calculus"
    - "multiparty session actors"

Connected through hyperedge HE-4 (induced by source paper "comparing deadlock free session typed processes"):
  with members:
    - "recursive session types revisited"
    - "from lock freedom to progress using session types"

Connected through hyperedge HE-5 (induced by source paper "session types with runtime adaptation overview and examples"):
  with members:
    - "parameterised multiparty 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)