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: "undecidable problems about timed automata"
  Abstract: We solve some decision problems for timed automata which were recently raised by S. Tripakis in [ Folk Theorems on the Determinization and Minimization of Timed Automata, in the Proceedings of the International Workshop FORMATS'2003, LNCS, Volume 2791, p. 182-188, 2004 ] and by E. Asarin in [ Challenges in Timed Languages, From Applied Theory to Basic Theory, Bulletin of the EATCS, Volume 83, p. 106-120, 2004 ]. In particular, we show that one cannot decide whether a given timed automaton is determinizable or whether the complement of a timed regular language is timed regular. We show that the problem of the minimization of the number of clocks of a timed automaton is undecidable. It is also undecidable whether the shuffle of two timed regular languages is timed regular. We show that in the case of timed B\"uchi automata accepting infinite timed words some of these problems are Pi^1_1-hard, hence highly undecidable (located beyond the arithmetical hierarchy).

Connected through hyperedge HE-1 (induced by source paper "control strategies for off line testing of timed systems"):
  with members:
    - "off line test selection with test purposes for non deterministic timed automata"

Connected through hyperedge HE-2 (induced by source paper "bounded determinization of timed automata with silent transitions"):
  with members:
    - "off line test selection with test purposes for non deterministic timed automata"

Connected through hyperedge HE-3 (induced by source paper "reducing clocks in timed automata while preserving bisimulation"):
  with members:
    - "better abstractions for timed automata"
    - "a unifying approach to decide relations for timed automata and their game characterization"
    - "small maximal independent sets and faster exact graph coloring"

Connected through hyperedge HE-4 (induced by source paper "almost periodicity and the timestamp of timed automata"):
  with members:
    - "bounded determinization of timed automata with silent transitions"

Connected through hyperedge HE-5 (induced by source paper "the timestamp of timed automata"):
  with members:
    - "bounded determinization of timed automata with silent transitions"

Connected through hyperedge HE-6 (induced by source paper "three applications to rational relations of the high undecidability of the infinite post correspondence problem in a regular omega language"):
  with members:
    - "highly undecidable problems for infinite computations"
    - "decision problems for turing machines"
    - "on the continuity set of an omega rational function"
    - "borel ranks and wadge degrees of context free omega languages"

Connected through hyperedge HE-7 (induced by source paper "highly undecidable problems for infinite computations"):
  with members:
    - "borel hierarchy and omega context free languages"
    - "on recognizable languages of infinite pictures"
    - "on the topological complexity of infinitary rational relations"
    - "highly undecidable problems about recognizability by tiling systems"
    - "borel ranks and wadge degrees of context free omega languages"

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)