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: "two for the price of one lifting separation logic assertions"
  Abstract: Recently, data abstraction has been studied in the context of separation#N#logic, with noticeable practical successes: the developed logics have enabled#N#clean proofs of tricky challenging programs, such as subject-observer patterns,#N#and they have become the basis of efficient verification tools for Java#N#(jStar), C (VeriFast) and Hoare Type Theory (Ynot). In this paper, we give a#N#new semantic analysis of such logic-based approaches using Reynolds's#N#relational parametricity. The core of the analysis is our lifting theorems,#N#which give a sound and complete condition for when a true implication between#N#assertions in the standard interpretation entails that the same implication#N#holds in a relational interpretation. Using these theorems, we provide an#N#algorithm for identifying abstraction-respecting client-side proofs; the proofs#N#ensure that clients cannot distinguish two appropriately-related module#N#implementations.

Connected through hyperedge HE-1 (induced by source paper "data abstraction and relational program logic"):
  with members:
    - "a general framework for relational parametricity"
    - "journey beyond full abstraction exploring robust property preservation for secure compilation"
    - "relational parametricity and separation logic"
    - "ownership confinement ensures representation independence for object oriented programs"

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)