Degree of Ball Maps with Maximum Geometric Rank

This work focuses on the degree bound of maps between balls with maximum geometric rank and minimum target dimension where this geometric rank occurs. Specifically, we show that rational proper maps between ${\mathbb{B}}_n$ and ${\mathbb{B}}_N$ with $n\ge 2$, $N=\frac{n(n+1)}{2}$, and geometric rank $n-1$ cannot have a degree of more than $n+1$.