# How does one \ref and \cite paragraphs in a mathematical text? (see picture)

How does one \ref and \cite partly mathematical "textblocks" that are in separated paragraphs?

Very good example here: A Short Proof of Fleischner's Theorem, page 4; there are textblocks (1) and (2) and they are referenced several times in the latter text.

Here is a pic of the desired result:

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Aren't this textblocks lemas or theorems? You could use the theorem package to define lemas, assertions, ... – TeXtnik Jan 8 '13 at 10:36
They are used exactly like , so that you get a (number) in the margin. Then you can cite the (number) in latter text. If I use {equation}, I get lots of errors or one really long line of \text{...} How do I get it to look like equation and have no errors? And be able to cite with a (number)? – Ohto Nordberg Jan 8 '13 at 11:03
@zunbeltz Do you mean \usepackage{amsthm}? It has theorems and I use them. – Ohto Nordberg Jan 8 '13 at 11:14

## 1 Answer

You can use an equation environment with an embedded array whose only column is in paragraph format. For example:

\documentclass{article}

\begin{document}
\noindent
following assertion holds:
$$\label{eq:test} \begin{array}{p{0.8\textwidth}} for any $$i,j$$, if $$v = x^i_j$$ then all passes of $$J'$$ through are marked except for the pass containing $$e^i_j$$. \end{array}$$
This is easy to verify\dots

So we assume that (\ref{eq:test}) holds\dots
\end{document}


This way you have the usual control that you are used to from equations. Feel free to adjust the width of the paragraph. I have chosen 0.8\textwidth. Some dimension is required.

The above solution may be packaged up into a dedicated environment as follows:

\documentclass{article}

\newenvironment{assertion}{$$\begin{array}{p{0.8\textwidth}}}{% \end{array}$$}

\begin{document}
\noindent
following assertion holds:
\begin{assertion}
\label{eq:test}
for any $$i,j$$, if $$v = x^i_j$$ then all passes of $$J'$$
through are marked except for the pass containing $$e^i_j$$.
\end{assertion}
This is easy to verify\dots

\end{document}

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Works perfect, thank you! – Ohto Nordberg Jan 8 '13 at 12:48