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: "pushdown timed automata a binary reachability characterization and safety verification"
  Abstract: We consider pushdown timed automata (PTAs) that are timed automata (with dense clocks) augmented with a pushdown stack. A configuration of a PTA includes a control state, dense clock values and a stack word. By using the pattern technique, we give a decidable characterization of the binary reachability (i.e., the set of all pairs of configurations such that one can reach the other) of a PTA. Since a timed automaton can be treated as a PTA without the pushdown stack, we can show that the binary reachability of a timed automaton is definable in the additive theory of reals and integers. The results can be used to verify a class of properties containing linear relations over both dense variables and unbounded discrete variables. The properties previously could not be verified using the classic region technique nor expressed by timed temporal logics for timed automata and CTL$^*$ for pushdown systems. The results are also extended to other generalizations of timed automata.

Connected through hyperedge HE-1 (induced by source paper "symbolic monitoring against specifications parametric in time and data"):
  with members:
    - "offline timed pattern matching under uncertainty"
    - "efficient online timed pattern matching by automata based skipping"
    - "montre a tool for monitoring timed regular expressions"
    - "verification for timed automata extended with unbounded discrete data structures"
    - "the parma polyhedra library toward a complete set of numerical abstractions for the analysis and verification of hardware and software systems"

Connected through hyperedge HE-2 (induced by source paper "effective definability of the reachability relation in timed automata"):
  with members:
    - "binary reachability of timed pushdown automata via quantifier elimination and cyclic order atoms"
    - "revisiting reachability in timed automata"
    - "parikh images of regular languages complexity and applications"

Connected through hyperedge HE-3 (induced by source paper "zenoness for timed pushdown automata"):
  with members:
    - "reachability analysis of communicating pushdown systems"
    - "a bi directional refinement algorithm for the calculus of co inductive constructions"
    - "efficient emptiness check for timed b uchi automata extended version"

Connected through hyperedge HE-4 (induced by source paper "zenoness for timed pushdown automata"):
  with members:
    - "reachability analysis of communicating pushdown systems"
    - "a bi directional refinement algorithm for the calculus of co inductive constructions"
    - "efficient emptiness check for timed b uchi automata extended version"

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)