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: "the algebraic intersection type unification problem"
  Abstract: The algebraic intersection type unification problem is an important component#N#in proof search related to several natural decision problems in intersection#N#type systems. It is unknown and remains open whether the algebraic intersection#N#type unification problem is decidable. We give the first nontrivial lower bound#N#for the problem by showing (our main result) that it is exponential time hard.#N#Furthermore, we show that this holds even under rank 1 solutions (substitutions#N#whose codomains are restricted to contain rank 1 types). In addition, we#N#provide a fixed-parameter intractability result for intersection type matching#N#(one-sided unification), which is known to be NP-complete.#N#  We place the algebraic intersection type unification problem in the context#N#of unification theory. The equational theory of intersection types can be#N#presented as an algebraic theory with an ACI (associative, commutative, and#N#idempotent) operator (intersection type) combined with distributivity#N#properties with respect to a second operator (function type). Although the#N#problem is algebraically natural and interesting, it appears to occupy a#N#hitherto unstudied place in the theory of unification, and our investigation of#N#the problem suggests that new methods are required to understand the problem.#N#Thus, for the lower bound proof, we were not able to reduce from known results#N#in ACI-unification theory and use game-theoretic methods for two-player tiling#N#games.

Connected through hyperedge HE-1 (induced by source paper "the delta calculus syntax and types"):
  with members:
    - "the delta framework"
    - "elaborating intersection and union 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.LO(Logic in Computer Science)