\begin{tabbing}
1. $T$ : Type
\\[0ex]2. $n$ : $\mathbb{Z}$
\\[0ex]3. 0 $<$ $n$
\\[0ex]4. $\forall$$h$, $f$:($T$$\rightarrow$($T$ + Top)). $f$\^{}$n$ {-} 1 o $h$   = primrec($n$ {-} 1;$h$;$\lambda$$i$,$g$. $f$ o $g$  )
\\[0ex]$\vdash$  \=$\forall$$h$, $f$:($T$$\rightarrow$($T$ + Top)).\+
\\[0ex]primrec($n$;p{-}id();$\lambda$$i$,$g$. $f$ o $g$  ) o $h$   = primrec($n$;$h$;$\lambda$$i$,$g$. $f$ o $g$  )
\-
\end{tabbing}