# How were these graphs obtained in N.L.S?

See attached pdf detailing some plots in $\mathbb{R}^2$. How were these graphs determined for 1-, and $\infty$- norms?
For $\infty$-norm, the inequality is max(|x|, |y|) <= 1, which is equivalent to |x| <= 1 and |y| <= 1, or -1 <= x, y <= 1.