Projection function
= Projection function
{title2=$\pi_i^k$}
The $i$th $k$-ary projection returns its $i$th input:
$$
\pi_i^k(x_1,\ldots,x_k)=x_i.
$$
= Projection function
{title2=$\pi_i^k$}
The $i$th $k$-ary projection returns its $i$th input:
$$
\pi_i^k(x_1,\ldots,x_k)=x_i.
$$