Deduce that there exists a constant $M \geq 0$ such that for all $n \in \mathbb { N } ^ { * }$, we have $$\left\| u - \hat { B } _ { n + 1 } u \right\| _ { \infty } \leq \frac { M } { n ^ { \alpha / 2 } }$$
Deduce that there exists a constant $M \geq 0$ such that for all $n \in \mathbb { N } ^ { * }$, we have
$$\left\| u - \hat { B } _ { n + 1 } u \right\| _ { \infty } \leq \frac { M } { n ^ { \alpha / 2 } }$$