Pour tout $C\,\bar u$ avec $C\in\FTyp$ et $\valabs{u}=\arity(C)$, alors $\mcal{I}_{C\bar u}\in\Candidates$.
\begin{lem}[Reducibility of $\mcal{I}_C$]
If $C\in\CTyp$, then $\mcal{I}_C\in\Candidates$.
\end{lem}
\begin{proof}
\begin{itemize}
\item
Si $C\in\CTyp$.
On a $\mcal{I}_{C\bar u}=K_{C\bar u}(\mcal{I}_{C\bar u})$.
\begin{itemize}
\item
Par définition de $K_{C\bar u}$, on a $K_{C\bar u}(\mcal{I}_{C\bar u})\subseteq\SN(\rew)$.
\item
Soit $t\in\mcal{I}_{C\bar u}$ et $u$ tel que $t\rew u$.
Comme $t\in\SN(\rew\cup\surterm_{acc})$, $u\in\SN(\rew\cup\surterm_{acc})$ aussi.
Si $u\reww c\,\bar v$, alors $t\reww c\,\bar v$ donc la contrainte de réductibilité des arguments accessibles est remplie.
\item
Let $t$ be a neutral term such that $\enscond{u}{t\rew u}\subseteq\mcal{I}_0(T)$.
Since $t$ is neutral, $\enscond{u}{t(\rew\cup\surterm_{acc}) u}=\enscond{u}{t\rew u}$, so $t\in\SN(\rew\cup\surterm_{acc})$.
If $t\reww c\,\bar v$, then there is a $u\in\enscond{u}{t\rew u}$ such that $u\reww c\,\bar v$ so the constraint on the reducibility of the accessible arguments are fulfilled.
\end{itemize}
\item
First note that $\mcal{I}_C=K_{\bar C}(\mcal{I}_C)$.
\begin{itemize}
\item
By definition of $K_{\bar C}$, we have $K_{\bar C}(\mcal{I}_C)\subseteq\SN(\rew)$.
\item
Let $t\in\mcal{I}_C$ and $u$ be such that $t\rew u$.
Since $t\in\SN(\rew\cup\surterm_{acc})$, $u\in\SN(\rew\cup\surterm_{acc})$ too.
If $u\reww c\,\bar v$, then $t\reww c\,\bar v$ so the constraint on the reducibility of the accessible arguments are fulfilled.
\item
Let $t$ be a neutral term such that $\enscond{u}{t\rew u}\subseteq\mcal{I}_C$.
Since $t$ is neutral, $\enscond{u}{t(\rew\cup\surterm_{acc}) u}=\enscond{u}{t\rew u}$, so $t\in\SN(\rew\cup\surterm_{acc})$.
If $t\reww c\,\bar v$, then there is a $u\in\enscond{u}{t\rew u}$ such that $u\reww c\,\bar v$ so the constraint on the reducibility of the accessible arguments are fulfilled.\qedhere
\end{itemize}
\end{proof}
\begin{lem}[Product of candidates]\label{lem-product-candidate}
If $P\in\Candidates$ and, for all $a\in P$, $Q(a)\in\Candidates$, then $\enscond{t}{\text{for all }a\in P. t\,a\in Q(a)}\in\Candidates$.