Derive the margin generalisation bound

Let $\Fcal_B$ be the norm-bounded linear class with $\|x_i\|_2\le R$, and fix $\gamma>0$. Prove that with probability at least $1-\delta$, for all $f\in\Fcal_B$,

$$\P\big(Yf(X)\le0\big) \le \frac1n\sum_i\one\{y_if(x_i)\le\gamma\} + \frac{2BR}{\gamma\sqrt n} + \sqrt{\frac{\log(1/\delta)}{2n}} .$$

Identify the surrogate loss, its Lipschitz constant, and the role of the contraction lemma.