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: "deciding equivalence with sums and the empty type"
  Abstract: The logical technique of focusing can be applied to the $\lambda$-calculus; in a simple type system with atomic types and negative type formers (functions, products, the unit type), its normal forms coincide with $\beta\eta$-normal forms. Introducing a saturation phase gives a notion of quasi-normal forms in presence of positive types (sum types and the empty type). This rich structure let us prove the decidability of $\beta\eta$-equivalence in presence of the empty type, the fact that it coincides with contextual equivalence, and a finite model property.

Connected through hyperedge HE-1 (induced by source paper "algebraic property graphs"):
  with members:
    - "algebraic data integration"
    - "reconciliation of rdf and property graphs"
    - "constructions from dots and lines"

Connected through hyperedge HE-2 (induced by source paper "bidirectional typing"):
  with members:
    - "the exp log normal form of types decomposing extensional equality and representing terms compactly"
    - "sums of uncertainty refinements go gradual"
    - "elaborating intersection and union types"

Connected through hyperedge HE-3 (induced by source paper "proving properties of polymorphic programs using type isomorphisms with the yoneda lemma"):
  with members:
    - "impredicative encodings of higher inductive types"
    - "proof nets coends and the yoneda isomorphism"

Connected through hyperedge HE-4 (induced by source paper "normalization by evaluation for call by push value and polarized lambda calculus"):
  with members:
    - "focusing and polarization in intuitionistic logic"

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)