Respuesta1
Puedes usar un regular tabular
:
\documentclass{article}
\usepackage{lipsum}
\newcommand{\algvrule}{@{\hspace{.5em}}|@{\hspace{1em}}}
\begin{document}
\lipsum[1]
\noindent
\begin{tabular}{@{} l @{}}
As before,~$k$ here is a commutative ring. \\
\begin{tabular}{\algvrule l @{}}
Hence could be a field of integers~$Z$; these are the usual choices. \\
\begin{tabular}{\algvrule l @{}}
Given an infinite variable set $x = (x_1; x_2; \ldots)$, a monomial \\
$x^p = x_1^a x_2^b \cdots$, is indexed by an element $t = (a; b; \ldots)$ in~$N^\infty$ \\
having finite support, such~$t$ are called weak compositions.
\end{tabular} \\
The nonzero ones among the integers $a; b; \ldots$ are called the parts of the
\end{tabular} \\
weak composition~$t$.
\end{tabular}
\lipsum[2]
\end{document}