The Swchartz, $\mathcal S(\mathbb R^d)=\left\{f\in C^{\infty}(\mathbb r^d): \sup_{x\in \mathbb R^d}(1+|x|^{2})^{\frac{k}{2}}\sum_{|\alpha\leq l|}|D^{\alpha}f(x)|< \infty\right\}$, for all $k, l \in \mathbb N_{0}, \alpha \in \mathbb R^d$.
Let $f \in \mathcal S(\mathbb R^d)$, the Fourier transform of f is given by $\hat{f}(\xi)=(2\pi)^{-\frac{d}{2}}\int_{\mathbb R^d}{e^{-ix.\xi}f(x)dx}$
And Sobolev Spaces, $H^{s}(\mathbb R^d)=\left\{f \in S'(\mathbb R^d): (1+|x|^{2})^{\frac{s}{2}}\hat{f}\in L^{2}(\mathbb R^d)\right\}, s\in \mathbb R$
By using the Fourier transform for that ($ s > d/2$) $f \in \mathcal S(\mathbb R^d)$, prove that $\left\|f\right\|_{L^{\infty}(\mathbb R^d)} \leq K \left\|f\right\|_{H^{s}(\mathbb R^d)}$, for some constant K.