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\bibitem{Vardi_Wolper_1986}
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M.~Y. Vardi and P.~Wolper, ``\BIBforeignlanguage{English}{An automata-theoretic
  approach to automatic program verification}.''\hskip 1em plus 0.5em minus
  0.4em\relax IEEE Computer Society, 1986. [Online]. Available:
  \url{https://orbi.uliege.be/handle/2268/116609}
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\bibitem{clarke2000model}
E.~M. Clarke, O.~Grumberg, and D.~A. Peled, \emph{Model Checking}.\hskip 1em
  plus 0.5em minus 0.4em\relax Cambridge, MA: MIT Press, 2000.

\bibitem{Kozen_1977}
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D.~Kozen, ``\BIBforeignlanguage{en}{Lower bounds for natural proof systems},''
  in \emph{\BIBforeignlanguage{en}{18th Annual Symposium on Foundations of
  Computer Science (sfcs 1977)}}.\hskip 1em plus 0.5em minus 0.4em\relax
  Providence, RI, USA: IEEE, Sep. 1977, p. 254–266. [Online]. Available:
  \url{http://ieeexplore.ieee.org/document/4567949/}
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