in https://www.coursehero.com/file/69596247/hw0pdf/ problem 3 asks to find a bijection between $\mathbb{N}$ and $\mathbb{N} \times \mathbb{N}=\mathbb{N}^2$.
Recalling Cantor diagonal proof it is easy to show that such bijection exists. I was wondering if there are other types of a simply linear maps that could give an explicit bijection.
Paolo