We have a metric on $\mathbb{R}^2$ defined as: $d(x,y) = \max(|x_1-y_1|,|x_2-y_2|)$ where $x = (x_1,x_2)$ and $y = (y_1,y_2)$. To satisfy the triangle inequality, we must show that $\max(|x_1-y_1|,|x_2-y_2|) \leq\max(|x_1-z_1|,|x_2-z_2|) +\max(|z_1-y_1|,|z_2-y_2|)$. I am having trouble formally proving this with the $max$ statements in there without hand waving. We know from properties of the absolute value that $|x+y| \leq |x| + |y|$. Can anyone show me a formal way to do this?
[Math] Showing that the Triangle Inequality holds for the $L_\infty$ norm as a metric.
inequalitymetric-spacesreal-analysis
Best Answer
Cases: