Consider the following code:
\documentclass{article}
\usepackage{graphicx}
\usepackage{bussproofs}
\newenvironment{bprooftree}
{\leavevmode\hbox\bgroup}
{\DisplayProof\egroup}
\begin{document}
\[
\begin{bprooftree}
\AxiomC{$ $}
\LeftLabel{R1:}
\UnaryInfC{s}
\end{bprooftree}
\qquad
\begin{bprooftree}
\AxiomC{$s_1,\cdots,s_n$}
\LeftLabel{R2:}
\UnaryInfC{s}
\end{bprooftree}
\]
\end{document}
As you can see from the picture R1 and R2 are not vertically aligned (at least not in the way a would like). How can I achieve a correct alignment?
Note: I do not remember exactly why I added the line with \newenvironment
but I think that it was due to the conflict with another package that I use: qtree
.