Let $x, y : \mathbb{N} \to [0, \infty)$ each be an D4686: Unsigned real sequence such that
(i) | \begin{equation} x \leq y \end{equation} |
Then
\begin{equation}
\sum_{n \in \mathbb{N}} x_n \leq \sum_{n \in \mathbb{N}} y_n
\end{equation}