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: "design and implementation of concurrent c0"
  Abstract: We describe Concurrent C0, a type-safe C-like language with contracts and session-typed communication over channels. Concurrent C0 supports an operation called forwarding which allows channels to be combined in a well-defined way. The language's type system enables elegant expression of session types and message-passing concurrent programs. We provide a Go-based implementation with language based optimizations that outperforms traditional message passing techniques.

Connected through hyperedge HE-1 (induced by source paper "back to futures"):
  with members:
    - "a message passing interpretation of adjoint logic"
    - "circular proofs as session typed processes a local validity condition"
    - "least and greatest fixed points in linear logic"

Connected through hyperedge HE-2 (induced by source paper "obsidian typestate and assets for safer blockchain programming"):
  with members:
    - "flint for safer smart contracts"
    - "towards safer smart contracts a survey of languages and verification methods"

Connected through hyperedge HE-3 (induced by source paper "gradual session types"):
  with members:
    - "gradual parametricity revisited"
    - "gradual liquid type inference"
    - "depending on session typed processes"
    - "fast and precise type checking for javascript"
    - "sums of uncertainty refinements go gradual"
    - "do be do be do"
    - "an erlang implementation of multiparty session actors"
    - "programming with algebraic effects and handlers"

Connected through hyperedge HE-4 (induced by source paper "work analysis with resource aware session types"):
  with members:
    - "verifying and synthesizing constant resource implementations with types"
    - "non blocking concurrent imperative programming with session types"
    - "the complexity of interaction"
    - "towards automatic resource bound analysis for ocaml"
    - "amortised resource analysis with separation logic"

Connected through hyperedge HE-5 (induced by source paper "a higher order logic for concurrent termination preserving refinement"):
  with members:
    - "step indexed relational reasoning for countable nondeterminism"

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)