二重否定導入

https://scrapbox.io/files/68aa4b1d7b89b3c95680da57.svg

code:proof.tikz(tex)

\usepackage{fitch}

\usepackage{amsmath}

\begin{document}

$\Large\begin{nd}

\hypo {1} {P}

\open

\hypo {2} {\lnot P}

\have {3} {P} \r{1}

\have {4} {\bot} \ie{2,3}

\close

\have {e} {\lnot\lnot P} \ii{2-4}

\end{nd}$

\end{document}