Added [simp]-lemmas "in_inv_image" and "in_lex_prod" in the spirit of "in_measure".
This simplifies some proofs.
\index{model checking example|(}%
\index{lfp@{\texttt{lfp}}!applications of|see{CTL}}
\input{CTL/document/Base.tex}
\input{CTL/document/PDL.tex}
\input{CTL/document/CTL.tex}
\index{model checking example|)}