I have the following code to produce a Fitch-style proof (for use with MathJax).
\def\fitch#1#2{\quad\begin{array}{|l}#1\\\hline#2\end{array}}
\fitch{A \to B \\ B \to C \\C \to D}{
A \to B\\
B \to C\\
\fitch{A}{
B \\
C \\
}\\
A \to C
}\\
Is it possible to modify it in order to auto-number each line in this way ?
Are there any environments, macros or perhaps another approach I could take ?
