I disagree with including this particular picture. Your picture is a picture of text. Moreover, the flow of logic is linear, unlike other possible uses of diagrams of text. IMO it is enough to write
- Premise: we are in a compact subset
- In compact subsets, every sequence must have an accumulation point
- Every sequence has an accumulation point
- Bolzano-Weierstrass: Every sequence has a convergent subsequence
and then explain separately that there are the relations $2\rightarrow 3 \leftrightarrow 4.$ Or perhaps,
Premise: we are in a compact subset
In compact subsets, every sequence must have an accumulation point
$\rightarrow$Every sequence has an accumulation point
$\leftrightarrow$Bolzano-Weierstrass: Every sequence has a convergent subsequence
Premise: we are in a compact subset
In compact subsets, every sequence must have an accumulation point<br/>
$\rightarrow$Every sequence has an accumulation point<br/>
$\leftrightarrow$Bolzano-Weierstrass: Every sequence has a convergent subsequence
If you must use this diagram, it is not so hard to reproduce it in MathJax (because it is rather simple), which I find preferable to the picture, but it doesn't feel worth the effort in this particular case:
$\newcommand{\mybox}[1]{\fbox{$\substack{#1}$}}
\newcommand{\dtext}[1]{\displaystyle\text{#1}}
\newcommand{\textone}{\dtext{Premise: we are in}\\\dtext{ a compact subset}}
\newcommand{\texttwo}{\dtext{In compact subsets, every}\\\dtext{sequence must have an}\\\dtext{accumulation point}}
\newcommand{\textthree}{\dtext{Every sequence has an}\\\dtext{accumulation point}}
\newcommand{\textfour}{\dtext{Bolzano-Weierstrass:}\\\dtext{Every sequence has a}\\\dtext{convergent subsequence}}
$
$$\fbox{$\begin{align}
&\mybox{\textone} \\ &
\begin{array}{ccccc}
\mybox{\texttwo}&\rightarrow&\mybox{\textthree}
\\&& \updownarrow
\\ && \mybox{\textfour}
\end{array}
\end{align}$}$$
$\newcommand{\mybox}[1]{\fbox{$\substack{#1}$}}
\newcommand{\dtext}[1]{\displaystyle\text{#1}}
\newcommand{\textone}{\dtext{Premise: we are in}\\\dtext{ a compact subset}}
\newcommand{\texttwo}{\dtext{In compact subsets, every}\\\dtext{sequence must have an}\\\dtext{accumulation point}}
\newcommand{\textthree}{\dtext{Every sequence has an}\\\dtext{accumulation point}}
\newcommand{\textfour}{\dtext{Bolzano-Weierstrass:}\\\dtext{Every sequence has a}\\\dtext{convergent subsequence}}
$
$$\fbox{$\begin{align}
&\mybox{\textone} \\ &
\begin{array}{ccccc}
\mybox{\texttwo}&\rightarrow&\mybox{\textthree}
\\&& \updownarrow
\\ && \mybox{\textfour}
\end{array}
\end{align}$}$$
See here for why we prefer text over images when possible.