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: "nominal unification from a higher order perspective"
  Abstract: Nominal logic is an extension of first-order logic with equality, name-binding, renaming via name-swapping and freshness of names. Contrarily to lambda-terms, in nominal terms, bindable names, called atoms, and instantiable variables are considered as distinct entities. Moreover, atoms are capturable by instantiations, breaking a fundamental principle of the lambda-calculus. Despite these differences, nominal unification can be seen from a higher-order perspective. From this view, we show that nominal unification can be quadratically reduced to a particular fragment of higher-order unification problems: higher-order pattern unification. We also prove that the translation preserves most generality of unifiers.

Connected through hyperedge HE-1 (induced by source paper "equivariant zfa and the foundations of nominal techniques"):
  with members:
    - "automata theory in nominal sets"
    - "pnl to hol from the logic of nominal sets to the logic of higher order functions"
    - "finite and infinite support in nominal algebra and logic nominal completeness theorems for free"

Connected through hyperedge HE-2 (induced by source paper "on nominal syntax and permutation fixed points"):
  with members:
    - "nominal c unification"
    - "nominal unification of higher order expressions with recursive let"
    - "nominal logic programming"

Connected through hyperedge HE-3 (induced by source paper "nominal unification of higher order expressions with recursive let"):
  with members:
    - "graph isomorphism in quasipolynomial time"
    - "general bindings and alpha equivalence in nominal isabelle"
    - "nominal logic programming"

Connected through hyperedge HE-4 (induced by source paper "pnl to hol from the logic of nominal sets to the logic of higher order functions"):
  with members:
    - "nominal logic programming"

Connected through hyperedge HE-5 (induced by source paper "constraint solving in non permutative nominal abstract syntax"):
  with members:
    - "heap reference analysis using access graphs"
    - "nominal logic programming"

Connected through hyperedge HE-6 (induced by source paper "closed nominal rewriting and efficiently computable nominal algebra equality"):
  with members:
    - "nominal logic programming"
    - "otter 3 3 reference manual"

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.LO(Logic in Computer Science)