Essay

$$\begin{array} { | c | c | c | } \hline \boldsymbol { A } & \boldsymbol { B } & \boldsymbol { f } ( \boldsymbol { A } , \boldsymbol { B } ) \\\hline 1 & 1 & 1 \\\hline 1 & 0 & 1 \\\hline 0 & 1 & 0 \\\hline 0 & 0 & 1 \\\hline\end{array}$$