\begin{tabbing}
(\=(((ExtWith [] [$A$$\rightarrow$$B$]) \+
\\[0ex]CollapseTHEN (Reduce 0))$\cdot$) 
\\[0ex]CollapseTHEN ((Auto\_aux (first\_nat 
\-\\[0ex]1:n) ((first\_nat 1:n),(first\_nat 3:n)) (first\_tok :t) inil\_term)))$\cdot$
\end{tabbing}