A small update is required in the proof in Box 3.1 at page 42

[eatam23]

In the the proof given in Box 3.1 at page 42, it is said that "A sequence $x_1, x_2,\cdots, \in \mathbb{R}$ is called Cauchy..." However, the correct thing should be $x_1, x_2,\cdots, \in \mathbb{R}^d$ since $x$ is a vector.

[MathFoundationRL]

Noted and thanks!