Q5

In the following truth table, $V = 1$ if and only if the input is valid.

$$\begin{array}{cc} \textbf{Inputs}&\textbf{Outputs}\\ \begin{array}{|c|c|c|c|} \hline {D_0}&D_1&D_2&D_3 \\ \hline 0&0&0&0 \\ \hline 1&0&0&0 \\ \hline \text{x}&1&0&0 \\ \hline \text{x}&\text{x}&1&0 \\ \hline \text{x}&\text{x}&\text{x}&1 \\ \hline \end{array}& \begin{array}{|c|c|c|} \hline X_0&X_1&V \\ \hline \text{x}&\text{x}&0\\ \hline 0&0&1\\ \hline 0&1&1\\ \hline 1&0&1\\ \hline 1&1&1\\ \hline \end{array} \\ \end{array}$$

What function does the truth table represent?