grandes-ecoles 2012 QIII.C.3

grandes-ecoles · France · centrale-maths1__mp Sequences and Series Properties and Manipulation of Power Series or Formal Series
Let $g \in C_{b}(\mathbb{R})$ with $N_{g}$ of finite codimension $n$ in $L^{1}(\mathbb{R})$, and let $\alpha_{1}, \ldots, \alpha_{n}$, $m_{1}, \ldots, m_{n}$ be as in III.C.1 such that $T_{\alpha}(g) = \sum_{i=1}^{n} m_{i}(\alpha) T_{\alpha_{i}}(g)$ for every real $\alpha$. By applying question III.C.2) to $V_{g}$, show that if $g$ is of class $C^{k}$ then the functions $m_{1}, \ldots, m_{n}$ are of class $C^{k}$.
Let $g \in C_{b}(\mathbb{R})$ with $N_{g}$ of finite codimension $n$ in $L^{1}(\mathbb{R})$, and let $\alpha_{1}, \ldots, \alpha_{n}$, $m_{1}, \ldots, m_{n}$ be as in III.C.1 such that $T_{\alpha}(g) = \sum_{i=1}^{n} m_{i}(\alpha) T_{\alpha_{i}}(g)$ for every real $\alpha$.\\
By applying question III.C.2) to $V_{g}$, show that if $g$ is of class $C^{k}$ then the functions $m_{1}, \ldots, m_{n}$ are of class $C^{k}$.