\begin{tabbing}
(\=without\_lemmas ``nat\_plus\_inc\_nat`` ((Unfold `subtype` 0) \+
\\[0ex]CollapseTHEN (
\-\\[0ex](Auto\_aux (first\_nat 1:n) ((first\_nat 2:n),(first\_nat 3:n)) (first\_tok :t) inil\_term)))$\cdot$)
\end{tabbing}