would the derivative of |_x_| be equal to 1? Or is it different because of the brackets?
Is the function even continuous? If you look at the function n,n+1)\mapsto\mathbb{R},\text{ }n\in\mathbb{N}" alt="fn,n+1)\mapsto\mathbb{R},\text{ }n\in\mathbb{N}" /> with then in fact . And so .