Computing all monomials of degree $n-1$ using $2n-3$ AND gates

We consider the vector-valued Boolean function $f:\{0,1{\}}^n\to \{0,1{\}}^n$ that outputs all $n$ monomials of degree $n-1$, i.e., $f_i(x)={\bigwedge }_{j\mathrm{\ne }i}{x}_j$, for $n\ge 3$. Boyar and Find have shown that the multiplicative complexity of this function is between $2n-3$ and $3n-6$. Determining its exact value has been an open problem that we address in this paper. We present an AND-optimal implementation of $f$ over the gate set $\{\text{AND},\text{XOR},\text{NOT}\}$, thus establishing that the multiplicative complexity of $f$ is exactly $2n-3$.