Suppose $N_1(t)$ and $N_2(t)$ are Poisson processes with intensities $\lambda_1$ and $\lambda_2$, respectively, both defined on the same probability space $(\Omega, \mathcal{F}, P)$ and relative to the same filtration $\mathcal{F}(t), t \geq 0$. Show that almost surely $N_1(t)$ and $N_2(t)$ can have no simultaneous jump. (Hint: Define the compensated Poisson processes $M_1(t)=N_1(t)-\lambda_1 t$ and $M_2(t)=N_2(t)-\lambda_2 t$, which like $N_1$ and $N_2$ are independent. Use Itô's product rule for jump processes to compute $M_1(t) M_2(t)$ and take expectations.)