\begin{tabbing}
(\=(((InstHyp [$a$;$b$] 4) \+
\\[0ex]CollapseTHENM (GenExRepD))$\cdot$) 
\\[0ex]CollapseTHENA ((Auto\_aux (first\_nat 
\-\\[0ex]1:n) ((first\_nat 1:n),(first\_nat 4:n)) (first\_tok :t) inil\_term)))$\cdot$
\end{tabbing}