# Using infer from the proof package?

I am using the \infer command from the proof package. Few things that I am trying to do unsuccessfully:

1. How can I have some space between the elements of the proof? such as space between x and y with \infer{x y}{z}. I can use \,, but there should be a better way to do it, I think.

2. \begin{center} has no effect on any of the inference rules, and I still want to be able to center them.

3. How would I set up space between the inference rules without using vspace? Right now, they appear very crowded, one right under the other.

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a tip: you can use backticks  to mark your inline code as Martin did in his edit. –  Hendrik Vogt Feb 13 '11 at 17:06

1. I guess you have to do the spacing manually, just like with any occurence of x y within the text.

2. You can center rules by $...$ and (depraceted) $$...$$.

3. You could adjust the length \inferLineSkip.

Here's a minimal example showing the tipps above:

\documentclass{article}
\usepackage{proof}
\setlength{\inferLineSkip}{4pt}
\begin{document}
\infer{B}{A & (A \rightarrow B)}
$\infer{xy}{z}$
\infer{C}{D & (D \leftarrow B)}
\end{document}
`

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works perfectly. thanks! –  kloop Feb 13 '11 at 17:37