How do I put annotations within my gather block?

Question

Possible Duplicate:
inserting sentences between subequations

I am proving a math theory in a gather block. I would like to annotate my proof. For instance,

\begin{gather}
... \\
By the inductive step,
... \\
\end{gather}

However, when I do so, the text meshes together in the generated pdf.

How do I put annotations within my gather block?

Answer 1

You can use \intertext from amsmath:

\documentclass{article}
\usepackage{amsmath}

\begin{document}
\begin{gather}
a = b \\
\intertext{By the inductive step,}
c = d
\end{gather}

\end{document}

The mathtools package offers you \shortintertext with reduced vertical spacing:

\documentclass{article}
\usepackage{mathtools}

\begin{document}

\begin{gather}
a = b \\
\shortintertext{By the inductive step,}
c = d
\end{gather}

\begin{gather}
a = b \\
\intertext{By the inductive step,}
c = d
\end{gather}

\end{document}