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: "complexity of universality and related problems for partially ordered nfas"
  Abstract: Abstract   Partially ordered NFAs (poNFAs) are NFAs where cycles occur only in the form of self-loops. A poNFA is universal if it accepts all words over its alphabet. Deciding universality is  PSpace  -complete for poNFAs. We show that this remains true when restricting to fixed alphabets. This is nontrivial since standard encodings of symbols in, e.g., binary can turn self-loops into longer cycles. A lower  coNP  -complete complexity bound is obtained if all self-loops in the poNFA are deterministic. We find that such restricted poNFAs (rpoNFAs) characterize    R   -trivial languages, and establish the complexity of deciding if the language of an NFA is    R   -trivial. The limitation to fixed alphabets is essential even in the restricted case: deciding universality of rpoNFAs with unbounded alphabets is  PSpace  -complete. Consequently, we obtain the complexity results for inclusion and equivalence problems. Finally, we show that the languages of rpoNFAs are definable by deterministic (one-unambiguous) regular expressions.

Connected through hyperedge HE-1 (induced by source paper "scattered factor universality of words"):
  with members:
    - "k spectra of weakly c balanced words"
    - "languages ordered by the subword order"
    - "computing the k binomial complexity of the thue morse word"
    - "testing simon s congruence"
    - "multivariate fine grained complexity of longest common subsequence"
    - "decidability complexity and expressiveness of first order logic over the subword ordering"
    - "the complexity of downward closure comparisons"
    - "on the index of simon s congruence for piecewise testability"

Connected through hyperedge HE-2 (induced by source paper "partially ordered automata and piecewise testability"):
  with members:
    - "the covering problem"
    - "complexity of detectability opacity and a diagnosability for modular discrete event systems"
    - "separability by piecewise testable languages is ptime complete"
    - "complexity of deciding detectability in discrete event systems"
    - "piecewise testable languages and nondeterministic automata"
    - "the height of piecewise testable languages and the complexity of the logic of subwords"
    - "on separation by locally testable and locally threshold testable languages"
    - "separating regular languages by piecewise testable and unambiguous languages"

Connected through hyperedge HE-3 (induced by source paper "anti alignments measuring the precision of process models and event logs"):
  with members:
    - "the reachability problem for petri nets is not elementary"
    - "the imprecisions of precision measures in process mining"
    - "automated discovery of process models from event logs review and benchmark"

Connected through hyperedge HE-4 (induced by source paper "on opacity verification for discrete event systems"):
  with members:
    - "the reachability problem for petri nets is not elementary"

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.FL(Formal Languages and Automata Theory)