Regular Sequence

Let there be two Particularly Well-Behaved Functions $F(x)$ and $p_\tau(x)$. If the limit

$$\lim_{\tau\to 0}\int_{-\infty}^\infty p_{\tau}(x)F(x)\,dx$$

exists, then $p_\tau(x)$ is a regular sequence of Particularly Well-Behaved Functions.